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An drea Sodi ,  Sandro Banfi ,  Michele Della Corte ,  Francesco Testa, Ilaria Passerini ,  Elisabetta Pelo ,  Settimio Rossi , and  Francesca Simonelli  |  Orphanet Journal of Rare Diseases |  Vol. 16 | Article 257 | 4 Jun 2021 |  doi.org/10.1186/s13023-021-01868-4 Inherited retinal dystrophy caused by confirmed biallelic mutations in the RPE65 gene, which encodes all-trans retinyl ester isomerase, an enzyme critical to the visual cycle, is a serious and sight-threatening autosomal recessive genetic disorder that causes a severe form of rod-cone mediated IRD that eventually progresses to complete blindness. Abstract Background This research aimed to establish recommendations on the clinical and genetic characteristics necessary to confirm patient eligibility for gene supplementation with voretigene neparvovec. Methods An expert steering committee comprising an interdisciplinary panel of Italian experts in the three fields of medical specialisation involved in the management of RPE65 -associated inherited retinal disease (IRD) (medical retina, genetics, vitreoretinal surgery) proposed clinical questions necessary to determine the correct identification of patients with the disease, determine the fundamental clinical and genetics tests to reach the correct diagnosis and to evaluate the urgency to treat patients eligible to receive treatment with voretigene neparvovec. Supported by an extensive review of the literature, a series of statements were developed and refined to prepare precisely constructed questionnaires that were circulated among an external panel of experts comprising ophthalmologists (retina specialists, vitreoretinal surgeons) and geneticists with extensive experience in IRDs in Italy in a two-round Delphi process. Results The categories addressed in the questionnaires included clinical manifestations of RPE65 -related IRD, IRD screening and diagnosis, gene testing and genotyping, ocular gene therapy for IRDs, patient eligibility and prioritisation and surgical issues. Response rates by the survey participants were over 90% for the majority of items in both Delphi rounds. The steering committee developed the key consensus recommendations on each category that came from the two Delphi rounds into a simple and linear diagnostic algorithm designed to illustrate the patient pathway leading from the patient’s referral centre to the retinal specialist centre. Conclusions Consensus guidelines were developed to guide paediatricians and general ophthalmologists to arrive at the correct diagnosis of RPE65 -associated IRD and make informed clinical decisions regarding eligibility for a gene therapy approach to RPE65 -associated IRD. The guidelines aim to ensure the best outcome for the patient, based on expert opinion, the published literature, and practical experience in the field of IRDs. Background Inherited retinal diseases (inherited retinal dystrophies; IRDs) are a heterogeneous group of ocular neurodegenerative disorders resulting from mutations in any one of over 250 causative genes [ 1 ]. They are mostly characterised by progressive retinal degeneration that leads to severe visual impairment and blindness [ 2 , 3 , 4 , 5 , 6 ]. Inherited retinal dystrophy caused by confirmed biallelic mutations in the RPE65 gene, which encodes all-trans retinyl ester isomerase, an enzyme critical to the visual cycle, is a serious and sight-threatening autosomal recessive genetic disorder that causes a severe form of rod-cone mediated IRD that eventually progresses to complete blindness [ 3 , 4 , 5 ]. The spectrum of RPE65 -mediated IRD exhibits common clinical findings, initially characterised by nyctalopia (night blindness), present from early childhood and due to a primary effect on the rod photoreceptors [ 7 , 8 ]. The visual function of individuals affected with IRD declines with age, with deteriorating visual acuity (VA) and progressive loss of retinal structure and function (retinal sensitivity) on visual field testing by Goldmann kinetic perimetry (GVF), often leading to blindness in young adulthood [ 8 , 9 , 10 , 11 ]. The disease course may include earlier or later onset, nystagmus, along with night blindness and loss of vision. Indeed, individuals with biallelic RPE65 mutations may be given one of a variety of clinical diagnoses. Depending on the time of disease onset, severity, rate of progression and presenting phenotype, the most common diagnoses are Leber congenital amaurosis (LCA) and early-onset severe retinal dystrophy (EOSRD) [ 5 , 8 ]. These forms are thought to be responsible for approximately 5% of cases of severe IRDs [ 7 ]. However, a smaller proportion of patients exhibit a milder phenotype with a slower progression, possibly associated with hypomorphic alleles [ 11 , 12 , 13 ]. Initially considered incurable, as the understanding of the pathophysiological mechanisms underlying the subtypes of IRD has expanded, a number of therapeutic approaches to treating IRDs have been proposed, the most advanced of which is gene supplementation therapy [ 6 ]. Monogenic ocular diseases are good candidates for gene transfer therapy, as the eye has favourable anatomical and immunological characteristics, providing a contained physical space protected by the blood-ocular barrier that is particularly suited for local delivery [ 14 ]. Remarkably, RPE65 -associated IRD represents a successful model for the development of ocular gene supplementation therapy applied to monogenic diseases. Click here to read entire article References Daiger SP, Sullivan LS, Browne SJ. RetNet: Summaries of Genes and Loci Causing Retinal Diseases (2020) The University of Texas-Houston Health Science Center. https://sph.uth.edu/retnet/sum-dis.htm . Accessed 29 May 2020 Hamel CP. Gene discovery and prevalence in inherited retinal dystrophies. C R Biol. 2014;337(3):160–6. Hohman TC. Hereditary retinal dystrophy. Handb Exp Pharmacol. 2017;242:337–67. Khan M, Fadaie Z, Cornelis SS, Cremers FPM, Roosing S. Identification and analysis of genes associated with inherited retinal diseases. Methods Mol Biol. 2019;18:343–427.   Kumaran N, Moore AT, Weleber RG, Michaelides M. Leber congenital amaurosis/early-onset severe retinal dystrophy: clinical features, molecular genetics and therapeutic interventions. Br J Ophthalmol. 2017;101(9):1147–54. Vázquez-Domínguez I, Garanto A, Collin RWJ. Molecular therapies for inherited retinal diseases-current standing, opportunities and challenges. Genes (Basel). 2019;10(9):654. den Hollander AI, Roepman R, Koenekoop RK, Cremers FP. Leber congenital amaurosis: genes, proteins and disease mechanisms. Prog Retin Eye Res. 2008;27(4):391–419. Thompson DA, Gyürüs P, Fleischer LL, et al. Genetics and phenotypes of RPE65 mutations in inherited retinal degeneration. Invest Ophthalmol Vis Sci. 2000;41(13):4293–9. Chung DC, Bertelsen M, Lorenz B, et al. The natural history of inherited retinal dystrophy due to biallelic mutations in the RPE65 gene. Am J Ophthalmol. 2019;199:58–70. Kumaran N, Georgiou M, Bainbridge JW, et al. Retinal structure in RPE65-associated retinal dystrophy. Investig Ophthalmol Vis Sci. 2020;61(4):47. Kumaran N, Rubin GS, Kalitzeos A, et al. A cross-sectional and longitudinal study of retinal sensitivity in RPE65-associated Leber congenital amaurosis. Investig Ophthalmol Vis Sci. 2018;59(8):3330–9. Hull S, Holder GE, Robson AG, et al. Preserved visual function in retinal dystrophy due to hypomorphic RPE65 mutations. Br J Ophthalmol. 2016;100(11):1499–505. Lorenz B, Poliakov E, Schambeck M, Friedburg C, Preising MN, Redmond TM. A comprehensive clinical and biochemical functional study of a novel RPE65 hypomorphic mutation. Investig Ophthalmol Vis Sci. 2008;49(12):5235–42.

Sarah Hull,  Nicholas Owen, Farrah Islam, Dhani Tracey-White, Vincent Plagnol, Graham E. Holder, Michel Michaelides, Keren Carss; F. Lucy Raymond, Jean-Michel Rozet, Simon C. Ramsden, Graeme C. M. Black, Isabelle Perrault, Ajoy Sarkar, Mariya Moosajee, Andrew R. Webster, Gavin Arno, Anthony T. Moore |  Investigative Ophthalmology & Visual Science | March 2016 | Vol. 57 | pgs. 1053-1062 | doi.org/10.1167/iovs.15-17976 Abstract Purpose : Mutations in the ciliary transporter gene IFT140, usually associated with a severe syndromic ciliopathy, may also cause isolated retinal dystrophy. A series of patients with nonsyndromic retinitis pigmentosa (RP) due to IFT140 was investigated in this study. Methods : Five probands and available affected family members underwent detailed phenotyping including retinal imaging and electrophysiology. Whole exome sequencing was performed on two probands, a targeted sequencing panel of 176 retinal genes on a further two, and whole genome sequencing on the fifth. Missense mutations of IFT140 were further investigated in vitro using transient plasmid transfection of hTERT-RPE1 cells. Results : Eight affected patients from five families had preserved visual acuity until at least the second decade; all had normal development without skeletal manifestations or renal failure at age 13 to 67 years (mean, 42 years; median, 44.5 years). Bi-allelic mutations in IFT140 were identified in all families including two novel mutations: c.2815T > C (p.Ser939Pro) and c.1422_23insAA (p.Arg475Asnfs*14). Expression studies demonstrated a significantly reduced number of cells showing localization of mutant IFT140 with the basal body for two nonsyndromic mutations and two syndromic mutations compared with the wild type and a polymorphism. Conclusions : This study highlights the phenotype of nonsyndromic RP due to mutations in IFT140 with milder retinal dystrophy than that associated with the syndromic disease. Introduction The outer segments of photoreceptors are highly modified, photosensitive cilia, which lack any capability for protein production. 1 Thus, they are reliant on the intraflagellar transport (IFT) system, which comprises large protein complexes for transport from the cell body to cilium tip and back driven by the motors kinesin-2 and dynein-2, respectively. 2 The IFT-B complex is essential for cilium assembly and anterograde transport, whereas the IFT-A complex is responsible for retrograde transport, with additional roles in anterograde transport by connecting kinesin to the IFT complex and in facilitating entry of proteins in to the cilium. 3 , 4 IFT140, a subunit of IFT-A, is vital for both the development and the maintenance of outer segments and has a specific role in opsin transport across the connecting cilium. 2   Mutations in IFT140 have been associated with Jeune asphyxiating thoracic dystrophy and Mainzer-Saldino syndrome, ciliopathies forming part of a spectrum of skeletal dysplasias now collectively termed short rib thoracic dysplasia 9 with or without polydactyly (SRTD9, mendelian inheritance in man [MIM]#266920). 5 – 7 First described in 1970, patients have variable skeletal features including shortened ribs, short stature, cone-shaped phalangeal epiphyses (prepubertal), brachymesophalangy, and acetabular spurring or metaphyseal defect of the femoral head. 8 Nonskeletal features in the majority of patients include a severe early-onset retinal dystrophy and end-stage renal failure secondary to nephronophthisis by the teenage years, with cerebellar ataxia, epilepsy, facial dysmorphism, learning difficulties, and cholestasis also reported. 5 – 7   Retinitis pigmentosa (RP) is the most common form of inherited retinal dystrophy, with more than 60 genes associated with the nonsyndromic, recessive form. 9 – 12 These include ciliopathy genes such as CEP290 and BBS1, which manifest both syndromic and nonsyndromic phenotypes. 13 , 14 Recently, IFT140 mutations have been identified in patients with isolated retinal dystrophy. 15 , 16 The present study reports eight patients from five families with isolated retinal dystrophy and bi-allelic IFT140 variants with detailed characterization of the ocular phenotype. Functional analysis of two of these variants with protein localization studies in hTERT-RPE1 cells supports their pathogenicity.  Click here to read entire article References Tsujikawa M, Malicki J. Intraflagellar transport genes are essential for differentiation and survival of vertebrate sensory neurons. Neuron . 2004; 42: 703–716. Crouse JA, Lopes VS, Sanagustin JT, Keady BT, Williams DS, Pazour GJ. Distinct functions for IFT140 and IFT20 in opsin transport. Cytoskeleton (Hoboken) . 2014; 71: 302–310. Mukhopadhyay S, Wen X, Chih B, et al. TULP3 bridges the IFT-A complex and membrane phosphoinositides to promote trafficking of G protein-coupled receptors into primary cilia. Genes Dev . 2010; 24: 2180–2193. Wei Q, Zhang Y, Li Y, Zhang Q, Ling K, Hu J. The BBSome controls IFT assembly and turnaround in cilia. Nat Cell Biol . 2012; 14: 950–957. Perrault I, Saunier S, Hanein S, et al. Mainzer-Saldino syndrome is a ciliopathy caused by IFT140 mutations. Am J Hum Genet . 2012; 90: 864–870. Schmidts M, Frank V, Eisenberger T, et al. Combined NGS approaches identify mutations in the intraflagellar transport gene IFT140 in skeletal ciliopathies with early progressive kidney Disease. Hum Mutat . 2013; 34: 714–724. Khan AO, Bolz HJ, Bergmann C. Early-onset severe retinal dystrophy as the initial presentation of IFT140-related skeletal ciliopathy. J AAPOS . 2014; 18: 203–205. Mainzer F, Saldino RM, Ozonoff MB, Minagi H. Familial nephropathy associated with retinitis pigmentosa, cerebellar ataxia and skeletal abnormalities. Am J Med . 1970; 49: 556–562. Bertelsen M, Jensen H, Bregnhøj JF, Rosenberg T. Prevalence of generalized retinal dystrophy in Denmark. Ophthalmic Epidemiol . 2014; 21: 217–223. Hartong DT, Berson EL, Dryja TP. Retinitis pigmentosa. Lancet . 2006; 368: 1795–1809. Xu Y, Guan L, Shen T, et al. Mutations of 60 known causative genes in 157 families with retinitis pigmentosa based on exome sequencing. Hum Genet . 2014;133(10):1255–1271. Littink KW, van den Born LI, Koenekoop RK, et al. Mutations in the EYS gene account for approximately 5% of autosomal recessive retinitis pigmentosa and cause a fairly homogeneous phenotype. Ophthalmology . 2010; 117: 2026–2033. den Hollander AI, Koenekoop RK, Yzer S, et al. Mutations in the CEP290 (NPHP6) gene are a frequent cause of Leber congenital amaurosis. Am J Hum Genet . 2006; 79: 556–561. Estrada-Cuzcano A, Koenekoop RK, Senechal A, et al. BBS1 mutations in a wide spectrum of phenotypes ranging from nonsyndromic retinitis pigmentosa to Bardet-Biedl syndrome. Arch Ophthalmol . 2012; 130: 1425–1432. Xu M, Yang L, Wang F, et al. Mutations in human IFT140 cause non-syndromic retinal degeneration. Hum Genet . 2015;134(10):1069–1078. Bifari IN, Elkhamary SM, Bolz HJ, Khan AO. The ophthalmic phenotype of IFT140-related ciliopathy ranges from isolated to syndromic congenital retinal dystrophy [published online ahead of print September 10 2015]. Br J Ophthalmol . doi:10.1136/bjophthalmol-2015-307555.

Jinyuan Wang , Jinlu Zhang , Shicheng Yu , Hongyan Li , Shaohong Chen , Jingting Luo , Haibo Wang , Yuxia Guan , Haihan Zhang , Shiyi Yin , Huili Wang , Heping Li , Junle Liu , Jingyuan Zhu , Qiong Yang , Ying Sha , Chuan Zhang , Yuhang Yang , Xuan Yang , Xifang Zhang , Xiuli Zhao , Likun Wang , Liping Yang , Wenbin Wei   | Signal Transduction and Targeted Therapy | Vol. 9, Issue 95 | 24 April 2024 | https://doi.org/10.1038/s41392-024-01806-3 Abstract Bietti crystalline corneoretinal dystrophy is an inherited retinal disease caused by mutations in CYP4V2 , which results in blindness in the working-age population, and there is currently no available treatment. Here, we report the results of the first-in-human clinical trial (NCT04722107) of gene therapy for Bietti crystalline corneoretinal dystrophy, including 12 participants who were followed up for 180–365 days. This open-label, single-arm exploratory trial aimed to assess the safety and efficacy of a recombinant adeno-associated-virus-serotype-2/8 vector encoding the human CYP4V2 protein (rAAV2/8-h CYP4V2 ). Participants received a single unilateral subretinal injection of 7.5 × 1010 vector genomes of rAAV2/8-h CYP4V2 . Overall, 73 treatment-emergent adverse events were reported, with the majority (98.6%) being of mild or moderate intensity and considered to be procedure- or corticosteroid-related; no treatment-related serious adverse events or local/systemic immune toxicities were observed. Compared with that measured at baseline, 77.8% of the treated eyes showed improvement in best-corrected visual acuity (BCVA) on day 180, with a mean ± standard deviation increase of 9.0 ± 10.8 letters in the 9 eyes analyzed ( p  = 0.021). By day 365, 80% of the treated eyes showed an increase in BCVA, with a mean increase of 11.0 ± 10.6 letters in the 5 eyes assessed ( p  = 0.125). Importantly, the patients’ improvement observed using multifocal electroretinogram, microperimetry, and Visual Function Questionnaire-25 further supported the beneficial effects of the treatment. We conclude that the favorable safety profile and visual improvements identified in this trial encourage the continued development of rAAV2/8-h CYP4V2 (named ZVS101e). Introduction Bietti crystalline corneoretinal dystrophy (BCD) is an inherited retinal degenerative disorder characterized by the presence of yellow-white crystalline deposits in the retina, which are accompanied by the progressive atrophy of the retinal pigment epithelium (RPE), photoreceptors, and choriocapillaris. Patients with BCD commonly exhibit clinical symptoms in their 20s or 30s, which include progressive night blindness, reduced visual acuity, restricted visual field, and impaired color vision. 1 According to a natural history study, the best-corrected visual acuity (BCVA) of patients with BCD typically declines by an average of 4.5 letters per year. 2 By the age of 50–60 years, most individuals with BCD experience severe visual and visual field impairments, resulting in legal blindness. 3 The worldwide prevalence of BCD is 1/576,000; 4 however, the condition is more common in East Asia. 5 In China, the prevalence of retinitis pigmentosa is 1/3784, 6 with BCD accounting for 15% of these cases; 7 thus, the prevalence of BCD in China is estimated to be ~1/25,000. Currently, no treatment is available for BCD. BCD is a specific type of retinitis pigmentosa with autosomal recessive inheritance caused by mutations in CYP4V2 . 8 The CYP4V2 protein is produced in multiple body tissues but is particularly abundant in the RPE. 9 , 10 CYP4V2 is an omega 3-polyunsaturated medium-chain fatty acid hydroxylase that hydrolyzes docosahexaenoic and eicosapentaenoic acid in the eye. 9 The photoreceptor outer segment contains large amounts of lipids that can be esterified to form docosahexaenoic acid, eicosapentaenoic acid, and other fatty acids. Physiologically, the RPE engulfs the portion of the photoreceptor outer segment that is undergoing shedding, and the disc lipids are metabolized in the RPE and transferred to the inner segment for the biosynthesis of new discs. This process of lipid recycling promotes disc regeneration while maintaining photoreceptor function. CYP4V2 mutations disrupt lipid metabolism and RPE-mediated lipid recirculation, thus impairing the regeneration of photoreceptor membrane discs, which leads to photoreceptor damage and, ultimately, retinal degeneration. 11 , 12 RPE65 gene replacement therapy was approved for marketing in 2017, as it represented a notable advance in clinical medicine and offered the potential to correct many other inherited retinal dystrophies (IRDs) caused by mutations that lead to functional impairment, including BCD. Adeno-associated virus (AAV)-mediated gene therapy has shown promising efficacy in several in vivo or in vitro BCD models. 12 , 13 , 14 , 15 In particular, the recombinant AAV2/8–human CYP4V2 (rAAV-h CYP4V2 ) vector, which produces the functional wild-type human CYP4V2 protein (patent no. CN113106124B), has been found to be efficient in an induced pluripotent stem cells-derived RPE from a patient with BCD as well as in a Cyp4v3- knockout mouse model, 14 providing the basis for a clinical trial for this gene therapy. Here, we report an investigator-initiated trial of gene replacement therapy for BCD. This is the first clinical trial on BCD worldwide with a focus on assessing the safety and preliminary clinical efficacy of rAAV2/8-h CYP4V2 , which will offer unprecedented prospects for addressing unmet medical needs in the management of BCD. Results Participant characteristics and intervention A total of 12 participants were enrolled in this study; the first 6 participants were followed up for 365 days, and the remaining 6 participants were followed up for 180 days. Their median age was 40 years (SD, 8.2 years; range, 27–50 years), and half of them were female (Table 1 ). One eye per patient was selected for treatment with rAAV2/8-h CYP4V2 . The median baseline visual acuity letter score in the treated eyes was 30.6 (Snellen equivalent, ~20/200; Table 1 ). Most participants exhibited widespread RPE and choriocapillaris atrophy, as well as ellipsoid zone disruption and extensive loss (Supplementary Figs. 1 and 2 ). The investigational product (rAAV2/8-h CYP4V2 , also known as ZVS101e ) was successfully injected into the subretinal space through one or two injection sites (retinotomies) per participant, with the fovea included in the administration area in 3 participants (R004, R007, and R008; Supplementary Fig. 2 ). The injected viral particles were fully absorbed within 24 hours. In 2 participants, R004 and R008, macular holes developed 1 day after surgery and healed 15 days after surgery (Supplementary Figs. 3 and 4 ). Participant R005 developed cataracts 1 day after the surgery and underwent lens replacement surgery 9 months after the intervention. Participant R002 was excluded from the efficacy analysis due to an accidental head trauma that occurred 27 days after surgery. Product safety 73 treatment-emergent adverse events (TEAEs) were reported in the 12 participants, including 24 ocular TEAEs and 49 systemic TEAEs. Ocular TEAEs were consistent with vitrectomy and subretinal injection procedures (Table 2 ). 2 serious adverse events occurred in 2 participants: R002 experienced a decrease in visual acuity due to head trauma by an accidental fall, and R005 developed cataracts after subretinal injection and underwent standard lens replacement surgery. The most common adverse event was coronavirus disease (COVID-19), followed by hypercholesterolemia and leukocytosis. No suspected unexpected serious adverse reaction was observed, and most of the TEAEs were mild (94.5%) or moderate (4.1%). 5 TEAEs (6.8%), including hyperlipidemia (4/73, 5.5%) and hypercholesterolemia (1/73, 1.4%), were considered to be possibly related to both the investigational product and corticosteroids; 32 TEAEs (43.8%) were considered to be related to corticosteroids; and 23 TEAEs (31.5%) were considered to be related to the procedure. Therefore, our analysis demonstrated that a single unilateral subretinal rAAV2/8-h CYP4V2 administration is safe and well-tolerated. Click here to read entire article References Yuzawa, M., Mae, Y. & Matsui, M. Bietti’s crystalline retinopathy. Ophthalmic Paediatr. Genet. 7, 9–20 (1986). Murakami, Y. et al. Genotype and long-term clinical course of Bietti crystalline dystrophy in Korean and Japanese patients. Ophthalmol. Retina 5, 1269–1279 (2021). Osman Saatci, A. & Can Doruk, H. An overview of rare and unusual clinical features of Bietti’s crystalline dystrophy. Med. Hypothesis Discov. Innov. Ophthalmol. 3, 51–56 (2014). Hanany, M., Rivolta, C. & Sharon, D. Worldwide carrier frequency and genetic prevalence of autosomal recessive inherited retinal diseases. Proc. Natl Acad. Sci. USA 117, 2710–2716 (2020).  Ng, D. S., Lai, T. Y., Ng, T. K. & Pang, C. P. Genetics of Bietti crystalline dystrophy. Asia Pac. J. Ophthalmol. 5, 245–252 (2016). Hu, D. Prevalence and mode of inheritance of major genetic eye diseases in China.pdf. J. Med. Genet. 24, 584–588 (1987). Gao, F. J. et al. Genetic and clinical findings in a large cohort of Chinese patients with suspected retinitis pigmentosa. Ophthalmology 126, 1549–1556 (2019). Li, A. et al. Bietti crystalline corneoretinal dystrophy is caused by mutations in the novel gene CYP4V2. Am. J. Hum. Genet. 74, 817–826 (2004). Nakano, M. et al. CYP4V2 in Bietti’s crystalline dystrophy: ocular localization, metabolism of ω-3-polyunsaturated fatty acids, and functional deficit of the p.H331P variant. Mol. Pharmacol. 82, 679–686 (2012). Jia, R. et al. AAV-mediated gene-replacement therapy restores viability of BCD patient iPSC derived RPE cells and vision of Cyp4v3 knockout mice. Hum. Mol. Genet. 32, 122–138 (2023). Hata, M. et al. Reduction of lipid accumulation rescues Bietti’s crystalline dystrophy phenotypes. Proc. Natl Acad. Sci. USA 115, 3936–3941 (2018). Zhang, Z. et al. PSCs reveal PUFA-provoked mitochondrial stress as a central node potentiating RPE degeneration in Bietti’s crystalline dystrophy. Mol. Ther. 28, 2642–2661 (2020). Qu, B. et al. Treating Bietti crystalline dystrophy in a high-fat diet-exacerbated murine model using gene therapy. Gene Ther. 27, 370–382 (2020). Jia, R. et al. AAV-mediated gene replacement therapy restores viability of BCD patient iPSC derived RPE cells and vision of Cyp4v3 knockout mice. Hum. Mol. Genet. 32, 122–138 (2022). Wang, J. H. et al. AAV2-mediated gene therapy for Bietti crystalline dystrophy provides functional CYP4V2 in multiple relevant cell models. Sci. Rep. 12, 9525 (2022).

Yun Wang , Liheng Guo , Su-Ping Cai , Meizhi Dai , Qiaona Yang, Wenhan Yu, Naihong Yan, Xiaomin Zhou, Jin Fu, Xinwu Guo, Pengfei Han, Jun Wang, Xuyang Liu | PLOS One | 31 May 2012 | doi.org/10.1371/journal.pone.0033673 Abstract Retinitis pigmentosa (RP) is a heterogeneous group of progressive retinal degenerations characterized by pigmentation and atrophy in the mid-periphery of the retina. Twenty two subjects from a four-generation Chinese family with RP and thin cornea, congenital cataract and high myopia is reported in this study. All family members underwent complete ophthalmologic examinations. Patients of the family presented with bone spicule-shaped pigment deposits in retina, retinal vascular attenuation, retinal and choroidal dystrophy, as well as punctate opacity of the lens, reduced cornea thickness and high myopia. Peripheral venous blood was obtained from all patients and their family members for genetic analysis. After mutation analysis in a few known RP candidate genes, exome sequencing was used to analyze the exomes of 3 patients III2, III4, III6 and the unaffected mother II2. A total of 34,693 variations shared by 3 patients were subjected to several filtering steps against existing variation databases. Identified variations were verified in the rest family members by PCR and Sanger sequencing. Compound heterozygous c.802-8_810del17insGC and c.1091-2A>G mutations of the CYP4V2 gene, known as genetic defects for Bietti crystalline corneoretinal dystrophy, were identified as causative mutations for RP of this family. Introduction Retinitis pigmentosa (RP) is a heterogeneous group of progressive retinal degenerations characterized typically by pigmentation and atrophy in the mid-periphery of the retina. It was estimated to affect 1 in 3500 in the general population [1] , [2] . Symptoms for RP include night blindness, tunnel vision and bone-spicule pigmentation in retina. Considerable clinical and genetic heterogeneity was demonstrated in RP patients, with wide variations in age of onset, severity, clinical phenotype, rate of progression and pattern of inheritance. Genotype-phenotype correlations are not strong enough to predict for RP. About 20–30% of patients with RP also presented with non-ocular disorders such as hearing loss, obesity, and cognitive impairment. Such cases fall within more than 30 different syndromes [3] . Over 50 genes have been identified to cause RP, but still only explain no more than half of the clinical cases [3] . Therefore, there has been limited success with approaches of screening of known candidate genes for RP by conventional Sanger sequencing. Fortunately, exome sequencing technique has come to the aid by enabling the identification of disease-associated mutations by sequencing the whole exome of a small number of affected individuals [4] – [6] . In the present study, disease-associated mutations were identified in a large Chinese family with RP complicated with congenital cataract, corneal thinning and high myopia using the exome sequencing techniques. Click here to read entire article References Humphries P, Kenna P, Farrar GJ (1992) On the molecular genetics of retinitis pigmentosa. Science 256: 804–808. Rivolta C, Sharon D, DeAngelis MM, Dryja TP (2002) Retinitis pigmentosa and allied diseases: numerous diseases, genes, and inheritance patterns. Hum Mol Genet 11: 1219–1227. Hartong DT, Berson EL, Dryja TP (2006) Retinitis pigmentosa. Lancet 368: 1795–1809. Choi M, Scholl UI, Ji W, Liu T, Tikhonova IR, et al. (2009) Genetic diagnosis by whole exome capture and massively parallel DNA sequencing. Proc Natl Acad Sci U S A 106: 19096–19101. Lalonde E, Albrecht S, Ha KC, Jacob K, Bolduc N, et al. (2010) Unexpected allelic heterogeneity and spectrum of mutations in Fowler syndrome revealed by next-generation exome sequencing. Hum Mutat 31: 918–923. Ng S B, Turner EH, Robertson PD, Flygare SD, Bigham AW, et al. (2009) Targeted capture and massively parallel sequencing of 12 human exomes. Nature 461: 272–276. Hoffman DR, Locke KG, Wheaton DH, Fish GE, Spencer R, et al. (2004) A randomized, placebo-controlled clinical trial of docosahexaenoic acid supplementation for X-linked retinitis pigmentosa. Am J Ophthalmol 137: 704–718. Li R, Li Y, Fang X, Yang H, Wang J, et al. (2009) SNP detection for massively parallel whole-genome resequencing. Genome Res 19: 1124–1132. Li G, Ma L, Song C, Ya ng Z, Wang X, et al. (2009) The YH database: the first Asian diploid genome database. Nucleic Acids Res 37: D1025–1028. Lai TY, Ng TK, Tam PO, Yam GH, Ngai JW, et al. (2007) Genotype phenotype analysis of Bietti’s crystalline dystrophy in patients with CYP4V2 mutations. Invest Ophthalmol Vis Sci 48: 5212–5220. Li A, Jiao X, Munier FL, Schorderet DF, Yao W, et al. 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Mingchu Xu, Yajing (Angela) Xie, Hana Abouzeid, Christopher T Gordon, Alessia Fiorentino, Zixi Sun, Anna Lehman, Ihab S Osman, Rachayata Dharmat, Rosa Riveiro-Alvarez, Linda Bapst-Wicht, Darwin Babino, Gavin Arno, Virginia Busetto, Li Zhao, Hui Li, Miguel A Lopez-Martinez, Liliana F Azevedo, Laurence Hubert, Nikolas Pontikos, Aiden Eblimit, Isabel Lorda-Sanchez, Valeria Kheir, Vincent Plagnol, Myriam Oufadem, Zachry T Soens, Lizhu Yang, Christine Bole-Feysot, Rolph Pfundt, Nathalie Allaman-Pillet, Patrick Nitschké, Michael E Cheetham, Stanislas Lyonnet, Smriti A Agrawal, Huajin Li, Gaëtan Pinton, Michel Michaelides, Claude Besmond, Yumei Li, Zhisheng Yuan, Johannes von Lintig, Andrew R Webster, Hervé Le Hir, Peter Stoilov, Jeanne Amiel, Alison J Hardcastle, Carmen Ayuso, Ruifang Sui, Rui Chen, Rando Allikmets, Daniel F Schorderet | American Journal Human Genetics | 2017 Apr 6 | 100(4) | pgs. 592-604 | doi: 10.1016/j.ajhg.2017.02.008 Abstract Pre-mRNA splicing factors play a fundamental role in regulating transcript diversity both temporally and spatially. Genetic defects in several spliceosome components have been linked to a set of non-overlapping spliceosomopathy phenotypes in humans, among which skeletal developmental defects and non-syndromic retinitis pigmentosa (RP) are frequent findings. Here we report that defects in spliceosome-associated protein CWC27 are associated with a spectrum of disease phenotypes ranging from isolated RP to severe syndromic forms. By whole-exome sequencing, recessive protein-truncating mutations in CWC27 were found in seven unrelated families that show a range of clinical phenotypes, including retinal degeneration, brachydactyly, craniofacial abnormalities, short stature, and neurological defects. Remarkably, variable expressivity of the human phenotype can be recapitulated in Cwc27 mutant mouse models, with significant embryonic lethality and severe phenotypes in the complete knockout mice while mice with a partial loss-of-function allele mimic the isolated retinal degeneration phenotype. Our study describes a retinal dystrophy-related phenotype spectrum as well as its genetic etiology and highlights the complexity of the spliceosomal gene network. Introduction Pre-mRNA splicing, which removes introns from eukaryotic transcripts, is an essential step in gene expression. Through the generation of numerous alternatively spliced transcript isoforms from the limited set of genes, the splicing process plays a critical role in giving rise to the protein diversity necessary to establish the complex structures and functions found throughout eukaryotes. 1 , 2 Splicing of pre-mRNA is catalyzed by the spliceosome, a ribonucleoprotein (RNP) complex that is dynamically assembled on each intron and undergoes several rearrangement steps before excising the intron. 3 The core of the spliceosome is formed by five small nuclear RNP (snRNP) particles and proteomic studies have identified more than 150 spliceosomal proteins including snRNP-specific proteins as well as miscellaneous non-snRNP splicing factors. 4 , 5 , 6 , 7 Though expressed ubiquitously, most spliceosomal genes associated with Mendelian disease have been classified within one of two non-overlapping phenotypic groups, suggesting tissue-specific functional roles. Mutations in splicing factors TXNL4A (MIM: 611595 ), 8 RBM8A (MIM: 605313 ), 9 SNRPB (MIM: 182282 ), 10 EIF4A3 (MIM: 608546 ), 11 EFTUD2 (MIM: 603892 ), 12 and SF3B4 (MIM: 605593 ) 13 cause syndromes mainly involving craniofacial and skeletal abnormalities, while disruptions of another group of spliceosomal genes— PRPF3 (MIM: 607301 ), 14 PRPF31 (MIM: 606419 ), 15 PRPF4 (MIM:  607795 ), 16 PRPF6 (MIM: 613979 ), 17 PRPF8 (MIM: 607300 ), 18 and SNRNP200 (MIM: 601664 ) 19 —lead to non-syndromic retinitis pigmentosa (RP), a restricted disease phenotype primarily affecting the rod photoreceptors. Recent next-generation sequencing approaches have allowed the identification of many of the disease-associated splicing factors listed above, but nevertheless the structural and functional roles of most spliceosome components and their involvement in human disease remain elusive. 20 Here, by exome sequencing in multiple families and disease modeling of two mouse alleles, we show that the disruption of the spliceosomal gene CWC27 (MIM: 617170 ) leads to a spectrum of isolated to syndromic phenotypes. The syndrome features include retinal degeneration, brachydactyly, craniofacial abnormalities, short stature, and neurological defects, with convergence of the two aforementioned non-overlapping spliceosomopathy phenotype groups. This study identifies a role for CWC27 both during early development and in the maintenance of mature tissues and highlights the complexity of spliceosome function. Click here to read entire article References Pan Q., Shai O., Lee L.J., Frey B.J., Blencowe B.J. 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Zou, T., Wang, T., Zhen, F., Dong, S., Gong, B., & Zhang, H. | Biomedical Reports | March 14, 2022 | 16, 40 | https://doi.org/10.3892/br.2022.1523 Abstract Retinitis pigmentosa (RP) belongs to a family of retinal disorders that is characterized by the progressive degeneration of rod and cone photoreceptors. The aim of the present study was to screen for possible disease‑causing genetic variants in a non‑consanguineous Chinese family with non‑syndromic autosomal recessive RP. Whole‑exome sequencing (WES) was performed in samples from the affected individual (the proband) and those from the two children of the proband. A novel compound heterozygous variant of c.C958T (p.R320X) and c.G1355A (p.R452H) in the Cytochrome P450 family 4 subfamily V member 2  ( CYP4V2 ) gene was identified through WES. Subsequently, this variant was validated by direct Sanger sequencing. This compound heterozygous variant was found to be absent from other unaffected family members and 400 ethnically‑matched healthy control individuals. In addition, this compound variant was co‑segregated with the RP phenotype in an autosomal recessive manner. In silico analysis revealed that both c.C958T (p.R320X) and c.G1355A (p.R452H) could compromise the protein function of CYP4V2. These results strongly suggest this compound variant to be a disease‑causing variant, which expands upon the spectrum of currently known CYP4V2 genetic variants associated with retinal diseases. Introduction Retinitis pigmentosa (RP; OMIM no. 268000) is a group of highly heterogeneous but related retinal disorders that cause progressive vision loss ( 1-3 ). Typically, RP manifests as night blindness in the early stages. As this disease progresses, the extent of visual field loss becomes gradually more apparent, with impaired color vision and fundus degeneration during the advanced stages. The prevalence of RP is ~1/4000 in China ( 4 , 5 ). RP can be classified as syndromic or non-syndromic. Usher syndrome and Bardet-Biedl syndrome, which also affect multiple organs, are the most common forms of syndromic RP. By contrast, non-syndromic RP is typically inherited and can manifest in an autosomal-recessive (50-60% of cases), autosomal-dominant (30-40% of cases), X-linked (5-15% of cases) or mitochondrial manner ( 6-8 ). In the pathophysiology of all types of RP, the majority of mutant genes reported are expressed exclusively in rod cells. Although a small number of mutants are specifically expressed in the retinal pigment epithelium, none are cone-specific ( https://sph.uth.edu/retnet/ ). Despite this, RP can cause the degeneration of both rod and cone photoreceptors, which mediate achromatic night vision and high acuity central vision, respectively ( 9-14 ). One of the reasons for the heterogeneity of RP is the >80 disease-causing genes that have been identified ( https://sph.uth.edu/retnet/ ). Additionally, variations in these genes can cause a wide range of clinical symptoms that are distinct from typical RP, including cone-rod dystrophy (CORD), Leber's congenital amaurosis (LCA) and stationary night blindness. For example, whilst a number of variants in the cone-rod homeobox ( CRX ) gene have been reported to be associated with RP, other variants of CRX can also trigger CORD and LCA ( 15-18 ). In another example, although the majority of Cytochrome P450 family 4 subfamily V member 2 ( CYP4V2 ) variants are associated with Bietti crystalline dystrophy (BCD), other variants in the gene can also cause RP. BCD is an autosomal recessive chorioretinal degenerative disease that is characterized by numerous glistening yellow-white crystalline retinal micro-deposits, progressive atrophy of the retinal pigment epithelium (RPE) and choroidal sclerosis ( 19 ). In the present study, whole-exome sequencing (WES) was applied to screen for potential disease-causing variants in a non-consanguineous Chinese family with autosomal recessive RP. A novel compound heterozygous variant in CYP4V2 was identified in a patient with RP. Click here to read the entire article

Have you or a family member been diagnosed with a CRX retinopathy? Mutations in the gene CRX has been associated with dominant inherited retinopathies Retinitis Pigmentosa (RP) Cone-Rod Dystrophy (CoRD) Leber Congenital Amaurosis (LCA) Dr. Shiming Chen (Opthalmology & Visual Sciences  – Washington University) has an exciting new study  and  is recruiting CRX families. Check out Dr. Chen Lab website to see the current projects. If you are interested in participating in this study, please contact Dr. Shiming Chen ( chenshiming@wustl.edu ) for further information Click here for additional details

Sayena Jabbehdari, MD, MPH, MBA; Florin Grigorian, MD; Michalis Georgiou, MD, PHD | Retina Today | November/December 2024 Retinal findings raised suspicion for this inherited retinal disease, confirmed with genetic testing. A 6-year-old boy with a positive family history of Best disease was referred to our pediatric retina clinic for evaluation due to decreased vision. His VA was 20/200 OD and 20/30 OS at presentation. Widefield pseudocolor images showed multifocal vitelliform material in each eye, along with choroidal neovascular membrane in his right eye (Figure 1). Figure 1. Widefield pseudocolor images showed multifocal vitelliform material in each eye, along with choroidal neovascular membrane in his right eye. OCT showed well-defined subretinal hyperreflective material in each eye with a subretinal hemorrhage in the right eye (Inset). Fundus autofluorescence images of each eye showed marked hyperautofluorescence corresponding to the subretinal vitelliform material (Figure 2). The patient underwent monthly injections of an antiVEGF agent in the right eye for treatment of the choroidal neovascular membrane. At the most recent visit, his VA had improved to 20/60 OD. GENETIC EVALUATION The patient had a family history of autosomal recessive bestrophinopathy in his siblings, cousin, and uncle, and his imaging findings were consistent with this condition. With genetic testing, the patient was found to be homozygous for the c.653G>A, p.(Arg218His) BEST1 variant, which was segregated to both parents. n Click here to see source article

Gabrielle Wheway, Liliya Nazlamova , Nervine Meshad, Samantha Hunt, Nicola Jackson, Amanda Churchill | "A combined in silico , in vitro and clinical approach to Characterize Novel Pathogenic Missense Variants in PRPF31 in Retinitis Pigmentosa" Overview At least six different proteins of the spliceosome, including PRPF3, PRPF4, PRPF6, PRPF8, PRPF31, and SNRNP200, are mutated in autosomal dominant retinitis pigmentosa (adRP). These proteins have recently been shown to localize to the base of the connecting cilium of the retinal photoreceptor cells, elucidating this form of RP as a retinal ciliopathy. In the case of loss-of-function variants in these genes, pathogenicity can easily be ascribed. In the case of missense variants, this is more challenging. Furthermore, the exact molecular mechanism of disease in this form of RP remains poorly understood. In this paper we take advantage of the recently published cryo EM-resolved structure of the entire human spliceosome, to predict the effect of a novel missense variant in one component of the spliceosome; PRPF31, found in a patient attending the genetics eye clinic at Bristol Eye Hospital. Monoallelic variants in PRPF31 are a common cause of autosomal dominant retinitis pigmentosa (adRP) with incomplete penetrance. We use in vitro studies to confirm pathogenicity of this novel variant PRPF31 c.341T > A, p.Ile114Asn. This work demonstrates how in silico modeling of structural effects of missense variants on cryo-EM resolved protein complexes can contribute to predicting pathogenicity of novel variants, in combination with in vitro and clinical studies. It is currently a considerable challenge to assign pathogenic status to missense variants in these proteins. Introduction Retinitis pigmentosa (RP) is a progressive retinal degeneration characterized by night blindness and restriction of peripheral vision. Later in the course of the disease, central and color vision can be lost. Many patients experience the first signs of RP between 20 and 40 years but there is much phenotypic variability from age of onset and speed of deterioration to severity of visual impairment ( Hartong et al., 2006 ). Retinitis pigmentosa, whilst classified as a rare disease, is the most common cause of inherited blindness worldwide. It affects between 1:3500 and 1:2000 people ( Golovleva et al., 2010 ; Sharon and Banin, 2015 ), and can be inherited in an autosomal dominant (adRP), autosomal recessive (arRP), or X-linked (xlRP) manner. It may occur in isolation (non-syndromic RP) ( Verbakel et al., 2018 ), or with other features (syndromic RP) as in Bardet–Biedl syndrome, Joubert syndrome and Usher syndrome ( Mockel et al., 2011 ). The condition is extremely heterogeneous, with 64 genes identified as causes of non-syndromic RP, and more than 50 genes associated with syndromic RP (RetNet 1 ). Even with current genetic knowledge, diagnostic detection rate in adRP cohorts remains between 40% ( Mockel et al., 2011 ) and 66% ( Zhang et al., 2016 ), suggesting that many disease genes remain to be identified, and many mutations within known genes require characterization to ascribe pathogenic status. Detection rates are as low as 14% in cohorts of simplex cases (single affected individuals) and multiplex cases (several affected individuals in one family but unclear pattern of inheritance) ( Jin et al., 2008 ). Such cases account for up to 50% of RP cases, so this presents a significant challenge to diagnosis ( Greenberg et al., 1993 ; Haim, 1993 ; Najera et al., 1995 ). The second most common genetic cause of adRP is PRPF31 , accounting for 6% of United States cases ( Sullivan et al., 2013 ) 8% of Spanish cases ( Martin-Merida et al., 2018 ), 8% of French Canadian cases ( Coussa et al., 2015 ), 8% of French cases ( Audo et al., 2010 ), 8.9% of cases in North America ( Daiger et al., 2014 ), 11.1% in small Chinese cohort ( Lim et al., 2009 ), 10% in a larger Chinese cohort ( Xu et al., 2012 ) and 10.5% of Belgian cases ( Van Cauwenbergh et al., 2017 ). However, this is likely to be an underestimate due to variable penetrance of this form of RP, complicating attempts to co-segregate the variant with clinical disease, making genetic diagnosis difficult. Whilst the majority of reported variants in PRPF31 are indels, splice site variants and nonsense variants, large-scale deletions or copy number variations ( Martin-Merida et al., 2018 ), which are easily ascribed pathogenic status, at least eleven missense variants in PRPF31 have been reported in the literature ( Table 1 ). Missense variants are more difficult to characterize functionally than nonsense or splicing mutations ( Cooper and Shendure, 2011 ) and it is likely that there are false negative diagnoses in patients carrying missense mutations due to lack of confidence in prediction of pathogenicity of such variants. This is reflected in the enrichment of PRPF31 missense variants labeled ‘uncertain significance’ in ClinVar, a public repository for clinically relevant genetic variants ( Landrum et al., 2014 , 2016 ). Furthermore, work has shown that some variants annotated as missense PRPF31 variants may in fact be affecting splicing of PRPF31 , introducing premature stop codons leading to nonsense mediated decay (NMD), a common disease mechanism in RP11 ( Rio Frio et al., 2008 ). One example is c.319C > G, which, whilst originally annotated as p.Leu107Val, actually affects splicing rather than an amino acid substitution ( Rio Frio et al., 2008 ). The presence of exonic splice enhancers is often overlooked by genetics researchers. Read entire article References Audo, I., Bujakowska, K., Mohand-Said, S., Lancelot, M. E., Moskova-Doumanova, V., Waseem, N. H., et al. (2010). Prevalence and novelty of PRPF31 mutations in french autosomal dominant rod-cone dystrophy patients and a review of published reports. BMC Med. Genet. 11:145. Cooper, G. M., and Shendure, J. (2011). Needles in stacks of needles: finding disease-causal variants in a wealth of genomic data. Nat. Rev. Genet. 12, 628–640. Coussa, R. G., Chakarova, C., Ajlan, R., Taha, M., Kavalec, C., Gomolin, J., et al. (2015). Genotype and phenotype studies in autosomal dominant retinitis pigmentosa (adrp) of the french canadian founder population. Invest. Ophthalmol. Vis. Sci. 56, 8297–8305. Daiger, S. P., Bowne, S. J., and Sullivan, L. S. (2014). Genes and mutations causing autosomal dominant retinitis pigmentosa. Cold Spring Harb. Perspect. Med. 5:a017129. Golovleva, I., Kohn, L., Burstedt, M., Daiger, S., and Sandgren, O. (2010). Mutation spectra in autosomal dominant and recessive retinitis pigmentosa in northern sweden. Adv. Exp. Med. Biol. 664, 255–262. Greenberg, J., Bartmann, L., Ramesar, R., and Beighton, P. (1993). Retinitis pigmentosa in southern africa. Clin. Genet. 44, 232–235. Haim, M. (1993). Retinitis pigmentosa: problems associated with genetic classification. Clin. Genet. 44, 62–70. Hartong, D. T., Berson, E. L., and Dryja, T. P. (2006). Retinitis pigmentosa. Lancet 368, 1795–1809. Jin, Z. B., Mandai, M., Yokota, T., Higuchi, K., Ohmori, K., Ohtsuki, F., et al. (2008). Identifying pathogenic genetic background of simplex or multiplex retinitis pigmentosa patients: a large scale mutation screening study. J. Med. Genet. 45, 465–472. Landrum, M. J., Lee, J. M., Benson, M., Brown, G., Chao, C., Chitipiralla, S., et al. (2016). ClinVar: public archive of interpretations of clinically relevant variants. Nucleic Acids Res. 44, D862–D868. Landrum, M. J., Lee, J. M., Riley, G. R., Jang, W., Rubinstein, W. S., Church, D. M., et al. (2014). ClinVar: public archive of relationships among sequence variation and human phenotype. Nucleic Acids Res. 42, D980–D985. Lim, K. P., Yip, S. P., Cheung, S. C., Leung, K. W., Lam, S. T., and To, C. H. (2009). Novel PRPF31 and PRPH2 mutations and co-occurrence of PRPF31 and RHO mutations in chinese patients with retinitis pigmentosa. Arch. Ophthalmol. 127, 784–790. Martin-Merida, I., Aguilera-Garcia, D., Fernandez-San Jose, P., Blanco-Kelly, F., Zurita, O., Almoguera, B., et al. (2018). Toward the mutational landscape of autosomal dominant retinitis pigmentosa: a comprehensive analysis of 258 spanish families. Invest. Ophthalmol. Vis. Sci. 59, 2345–2354. Mockel, A., Perdomo, Y., Stutzmann, F., Letsch, J., Marion, V., and Dollfus, H. (2011). Retinal dystrophy in Bardet-Biedl syndrome and related syndromic ciliopathies. Prog. Retin. Eye Res. 30, 258–274. Najera, C., Millan, J. M., Beneyto, M., and Prieto, F. (1995). Epidemiology of retinitis pigmentosa in the valencian community (Spain). Genet. Epidemiol. 12, 37–46. Rio Frio, T., Wade, N. M., Ransijn, A., Berson, E. L., Beckmann, J. S., and Rivolta, C. (2008). Premature termination codons in PRPF31 cause retinitis pigmentosa via haploinsufficiency due to nonsense-mediated mRNA decay. J. Clin. Invest. 118, 1519–1531. Schaffert, N., Hossbach, M., Heintzmann, R., Achsel, T., and Luhrmann, R. (2004). RNAi knockdown of hPrp31 leads to an accumulation of U4/U6 di-snRNPs in Cajal bodies. EMBO J. 23, 3000–3009. Sharon, D., and Banin, E. (2015). Nonsyndromic retinitis pigmentosa is highly prevalent in the jerusalem region with a high frequency of founder mutations. Mol. Vis. 21, 783–792. Sullivan, L. S., Bowne, S. J., Birch, D. G., Hughbanks-Wheaton, D., Heckenlively, J. R., Lewis, R. A., et al. (2006). Prevalence of disease-causing mutations in families with autosomal dominant retinitis pigmentosa: a screen of known genes in 200 families. Invest. Ophthalmol. Vis. Sci. 47, 3052–3064. Sullivan, L. S., Bowne, S. J., Reeves, M. J., Blain, D., Goetz, K., Ndifor, V., et al. (2013). Prevalence of mutations in eyeGENE probands with a diagnosis of autosomal dominant retinitis pigmentosa. Invest. Ophthalmol. Vis. Sci. 54, 6255–6261. doi: 10.1167/iovs.13-12605 Van Cauwenbergh, C., Coppieters, F., Roels, D., De Jaegere, S., Flipts, H., De Zaeytijd, J., et al. (2017). Mutations in splicing factor genes are a major cause of autosomal dominant retinitis pigmentosa in belgian families. PLoS One 12:e0170038. Verbakel, S. K., van Huet, R. A. C., Boon, C. J. F., den Hollander, A. I., Collin, R. W. J., Klaver, C. C. W., et al. (2018). Non-syndromic retinitis pigmentosa. Prog. Retin. Eye Res. 66, 157–186. Xu, F., Sui, R., Liang, X., Li, H., Jiang, R., and Dong, F. (2012). Novel PRPF31 mutations associated with chinese autosomal dominant retinitis pigmentosa patients. Mol. Vis. 18, 3021–3028. Zhang, Q., Xu, M., Verriotto, J. D., Li, Y., Wang, H., Gan, L., et al. (2016). Next-generation sequencing-based molecular diagnosis of 35 Hispanic retinitis pigmentosa probands. Sci. Rep. 6:32792.

P aul F Kenna, Marian M Humphries, Anna-Sophia Kiang, Philippe Brabet, Laurent Guillou, Ema Ozaki, Matthew Campbell, G Jane Farrar, Robert Koenekoop, Pete Humphries | BMJ Open Ophthalmology  | 2020 | 5:e000462 | doi: 10.1136/bmjophth-2020-00046 Abstract Objectives: No therapeutic interventions are currently available for autosomal dominant retinitis pigmentosa (adRP). An RPE65 Asp477Gly transition associates with late-onset adRP, reduced RPE65 enzymatic activity being one feature associated with this dominant variant. Our objective: to assess whether in a proof-of-concept study, oral synthetic 9 cis -retinyl acetate therapy improves vision in such advanced disease. Methods and analysis: A phase 1b proof-of-concept clinical trial was conducted involving five patients with advanced disease, aged 41-68 years. Goldmann visual fields (GVF) and visual acuities (VA) were assessed for 6-12 months after 7-day treatment, patients receiving consecutive oral doses (40 mg/m2) of 9- cis- retinyl acetate, a synthetic retinoid replacement. Results: Pathological effects of D477G variant were preliminarily assessed by electroretinography in mice expressing AAV-delivered D477G RPE65, by MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxyme- thoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium] assays on RPE viability and enzyme activity in cultured cells. In addition to a mild dominant effect reflected in reduced electroretinographics in mice, and reduced cellular function in vitro , D477G exhibited reduced enzymatic RPE65 activity in vitro . In patients, significant improvements were observed in GVF from baseline ranging from 70% to 200% in three of five subjects aged 67-68 years, with largest improvements at 7-10 months. Of two GVF non-responders, one had significant visual acuity improvement (5-15 letters) from baseline after 6 months. Conclusion: Families with D477G variant have been identified in Ireland, the UK, France, the USA and Canada. Effects of single 7-day oral retinoid supplementation lasted at least 6 months, possibly giving visual benefit throughout remaining life in patients with advanced disease, where gene therapy is unlikely to prove beneficial. Introduction Mutations in genes encoding enzymatic components of the retinoid cycle, reducing the availability of 11- cis -retinal, have been encountered in recessive forms of inherited retinal degenerations (IRDs), retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA). 1 In principle, administration of 11- cis -retinal would assist in preventing retinal degeneration in those IRDs where mutations within genes of the retinoid cycle are present. While 11- cis -retinal is unstable and not suitable for pharmacological use, 9- cis -retinal can be used as a replacement, forming iso-rhodopsin which retains function in photon capture and which has been shown, following intravitreal inoculation, to improve vision in dogs with null mutations within the RPE65 gene. 2 QLT091001 (9- cis -retinyl acetate) is a late-stage synthetic retinoid replacement therapy being developed for inherited retinal diseases in humans (Retinagenix). It is a prodrug, converted by hydrolysis in vivo to 9- cis -retinol, which is then converted to 9- cis -retinal, thus restoring the key biochemical component of the retinoid cycle. QLT091001 treatment has previously been shown to result in vision improvement (VA) and/or visual field (VF) in subjects with LCA or RP due to recessive mutations in either RPE65 or LRAT genes. 3 4 The mutation, D477G in exon 13 of the RPE65 gene is the only mutation within this gene so far identified manifesting autosomal dominant transmission. 5 Families displaying this dominant mutation have now been identified in Ireland, the UK, France, the USA and Newfoundland (Professor J. Green, personal communication). 5–7 Knock-in mice expressing D477G allele have deficits in retinal structure and function, with disruption of the visual cycle, indicative of decreased RPE65 enzymatic activity. Shin et al reported slower regeneration of 11- cis -retinaldehyde with lower electroretinographic (ERG) a-wave recovery following photobleaching, indicating delayed dark adaptation. 8 Choi et al conclude from X-ray crystallographic structural analysis that a possible mechanism for photoreceptor degeneration may involve D477G RPE65 cellular toxicity. 9 They also observed retinyl ester accumulation and slower regeneration of 11- cis -retinal after photobleaching in knock-in mice aged 9 months, and slow thinning of the retinal outer nuclear layer accompanied by decline in scotopic and photopic ERG, indicating loss of cone and rod photoreceptor function. Our in vitro data confirm a reduced enzymatic activity of the variant of approximately 25%. However, aberrant splicing of D477G transcripts has recently been suggested as an alternative mechanism contributing to reduced enzymatic activity and ultimately photoreceptor degeneration. 10 Hence, in vitro data may not accurately reflect the reduction in enzymatic activity occurring in vivo . Nevertheless, it can be strongly inferred that a component of the disease process in this very slowly progressing dominant retinopathy is limited availability of chromophore 11- cis -retinal and that oral synthetic retinoid therapy may be extendable in improving remaining vision in patients with this genetic subtype of disease, where, as yet, no means of prevention are available for any form of dominant RP. We report here further observations on the molecular pathology of the disease relevant to a pilot proof-of-concept study in which effects of a single 1 week course of oral retinoid therapy were assessed, and where VFs were significantly improved in three of five patients with advanced disease over periods of 6 months to 1 year. While previous studies on recessive LCA and RP have indicated maximum increases in VA at 2 months following retinoid treatment, responders in the current study were older (average age 62 years) and showed improvements over longer periods lasting over 6–12 months, which we suggest is a possible reflection of the time taken for regeneration of outer segments in remaining photoreceptors in these patients. Click here to read entire article Reference Tsin A, Betts-Obregon B, Grigsby J, et al. Visual cycle proteins: structure, function, and roles in human retinal disease. J Biol Chem 2018; 293:13016–21. Gearhart PM, Gearhart C, Thompson DA, et al. Improvement of visual performance with intravitreal administration of 9-cis-retinal in Rpe65-mutant dogs. Arch Ophthalmol 2010; 128:1442–8. Koenekoop RK, Sui R, Sallum J, et al. Oral 9-cis retinoid for childhood blindness due to Leber congenital amaurosis caused by RPE65 or LRAT mutations: an open-label phase 1B trial. Lancet 2014; 384:1513–20. Scholl HPN, Moore AT, Koenekoop RK, et al. Safety and Proof-of-Concept Study of Oral QLT091001 in Retinitis Pigmentosa Due to Inherited Deficiencies of Retinal Pigment Epithelial 65 Protein (RPE65) or Lecithin:Retinol Acyltransferase (LRAT). PLoS One 2015; 10. Bowne SJ, Humphries MM, Sullivan LS, et al. A dominant mutation in RPE65 identified by whole-exome sequencing causes retinitis pigmentosa with choroidal involvement. Eur J Hum Genet 2011; 19:1074–81. Jauregui R, Park KS, Tsang SH, et al. Two-Year progression analysis of RPE65 autosomal dominant retinitis pigmentosa. Ophthalmic Genet 2018; 39:544–9. Hull S, Mukherjee R, Holder GE, et al. The clinical features of retinal disease due to a dominant mutation in RPE65. Mol Vis 2016; 22:626–35. Shin Y, Moiseyev G, Chakraborty D, et al. A dominant mutation in RPE65, D477G, delays dark adaptation and disturbs the visual cycle in the mutant knock-in mice. Am J Pathol 2017; 187:517–27. Shin Y, Moiseyev G, Chakraborty D, et al. A dominant mutation in RPE65, D477G, delays dark adaptation and disturbs the visual cycle in the mutant knock-in mice. Am J Pathol 2017; 187:517–27. Choi EH, Suh S, Sander CL, et al. Insights into the pathogenesis of dominant retinitis pigmentosa associated with a D477G mutation in RPE65. Hum Mol Genet 2018; 27:2225–43. Li Y, Furhang R, Ray A, et al. Aberrant RNA splicing is the major pathogenic effect in a knock-in mouse model of the dominantly inherited c.1430A>G human RPE65 mutation. Hum Mutat 2019; 40:426–43. Palfi A, Chadderton N, O'Reilly M, et al. Efficient gene delivery to photoreceptors using AAV2/rh10 and rescue of the Rho(-/-) mouse. Mol Ther Methods Clin Dev 2015; 2:15016. Dagnelie G. Conversion of planimetric visual field data into solid angles and retinal areas. Clin Vis Sci 1990; 5:95–100. Berson EL, Rosner B, Sandberg MA, et al. A randomized trial of vitamin A and vitamin E supplementation for retinitis pigmentosa. Arch Ophthalmol 1993; 111:761–72. Cory AH, Owen TC, Barltrop JA, et al. Use of an aqueous soluble tetrazolium/formazan assay for cell growth assays in culture. Cancer Commun 1991; 3:207–12. Penha FM, Pons M, Costa EF, et al. Retinal pigmented epithelial cells cytotoxicity and apoptosis through activation of the mitochondrial intrinsic pathway: role of indocyanine green, brilliant blue and implications for chromovitrectomy. PLoS One 2013; 8. Bittner AK, Iftikhar MH, Dagnelie G, et al. Test-Retest, within-visit variability of Goldmann visual fields in retinitis pigmentosa. Invest Ophthalmol Vis Sci 2011; 52:8042–6.

Xue Wang ,  Chaofeng Yu ,  Radouil T. Tzekov ,  Yihua Zhu,  and  Wensheng Li |  Orphanet Journal of Rare Diseases |  Vol 15 (49) | 14 Feb 2020 | doi.org/10.1186/s13023-020-1304-1 Abstract Background RPE65 -associated LCA ( RPE65 -LCA) is an inherited retinal degeneration caused by the mutations of RPE65 gene and gene therapy has been developed to be a promising treatment. This study aims to evaluate the association between changes in visual function and application of gene therapy in patients with RPE65 -LCA. Methods Several databases (PubMed, Cochrane Library, and Web of Science) were searched for results of studies describing efficacy of gene therapy in patients with RPE65 -LCA. Six studies, which included one randomized and five prospective non-randomized clinical trials, 164 eyes met our search criteria and were assessed. Results The BCVA significantly improved in treated eyes at 1 yr post treatment by − 0.10 logMAR (95% CI, − 0.17 - -0.04; p  = 0·002), while there was no significant difference at 2–3 years post treatment (WMD: 0.01; 95% CI, − 0.00 - 0.02; p = 0·15). FST sensitivity to blue flashes also improved by 1.60 log (95% CI, 0.66–2.55; p  = 0.0009), but no significant difference to red flashes (WMD: 0.86; 95% CI, − 0·29–2.01; p  = 0.14) at 1 yr. There was no significant difference in central retinal thickness at 1 yr, but central retina in treated eyes appeared thinner at 2–3 years post treatment by 19.21 μm (95% CI, − 34.22 - -4.20; p  = 0.01). Conclusions Human gene therapy is a pioneering treatment option for RPE65 -LCA. Although its efficacy appears to be limited to less than 2 yrs after treatment, it carries the potential for further improvement and prolongation of efficacy. Background Leber’s Congenital Amaurosis (LCA) is a heterogeneous group of eye diseases with mostly autosomal recessive inheritance, characterized with nystagmus and severely decreased visual acuity in early infancy and complete blindness by the third-to-forth decade of life [ 1 ]. RPE65 -associated LCA ( RPE65 -LCA) is associated with mutations of the RPE65 gene encoding the retinoid isomerohydrolase in the retinal pigment epithelium (RPE), which result in rod-cone type retinal dystrophy [ 2 ] [ 3 ]. As a cutting-edge approach, human gene therapy was developed to compensate genetic deficiency and improve visual function of RPE65 -LCA as early as 2008 [ 4 , 5 , 6 ]. Since then several studies reported that RPE65 gene therapy could improve visual function in RPE65 -LCA; however, the overall level of efficacy remains somewhat uncertain and variable. Therefore, we systemically searched and analyzed the published literature in order to gain a better understanding of the effectiveness of human gene therapy on visual function in RPE65 -LCA. The proof of principle of gene therapy for RPE65 -associated IRD was demonstrated in murine and canine models of LCA [ 15 , 16 , 17 ], in which a recombinant adeno-associated viral vector serotype 2 (AAV2) gene replacement therapy produced encouraging improvements in visual function. This led to a clinical trials programme that confirmed the safety, durable efficacy, and favourable benefit-to-risk profile of voretigene neparvovec (AAV2-h RPE65 v2, voretigene neparvovec-rzyl, LUXTURNA™; Spark Therapeutics, Inc, Philadelphia, PA, USA, Novartis, Basel, Switzerland), administered as a (one-time) sub-retinal injection, in improving retinal and visual function in RPE65 -mediated IRD [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. Voretigene neparvovec received marketing authorisation for the US in 2017 [ 31 ] and the European Union in 2018 [ 32 ] for the treatment of adult and paediatric patients with vision loss due to IRD related to confirmed RPE65 biallelic mutations and who have sufficient viable retinal cells [ 32 ]. A precise genetic diagnosis is necessary to establish eligibility for treatment of RPE65 -associated IRD and to optimise the use of a precision therapeutic intervention such as voretigene neparvovec in a clinically and genetically heterogeneous group of IRDs. Not only is there a lack of shared criteria for the selection of patients suitable for RPE65 gene therapy, but the cost and complexity of the procedure mean that an equitable and transparent process for evaluating the urgency to treat for eligible patients is also necessary. In the absence of specific national guidance in this area, the goal of this project was to develop a clinical pathway algorithm that sets forth a stepwise process for ophthalmologists and geneticists to make decisions about the correct diagnosis and treatment with voretigene neparvovec of patients with RPE65 -associated IRD. Herein, we report the outcomes of a consensus process by a group of Italian experts in IRDs to establish recommendations on the clinical and genetic characteristics necessary to confirm patient eligibility for gene therapy with voretigene neparvovec. Click here to read entire study References Allikmets R. Leber congenital amaurosis: a genetic paradigm. Ophthalmic Genet. 2004;25(2):67–79. Lorenz B, Gyurus P, Preising M, Bremser D, Gu S, Andrassi M, Gerth C, Gal A. Early-onset severe rod-cone dystrophy in young children with RPE65 mutations. Invest Ophthalmol Vis Sci. 2000;41(9):2735–42. Redmond TM, Poliakov E, Yu S, Tsai JY, Lu Z, Gentleman S. Mutation of key residues of RPE65 abolishes its enzymatic role as isomerohydrolase in the visual cycle. Proc Natl Acad Sci U S A. 2005;102(38):13658–63. Bainbridge JW, Smith AJ, Barker SS, Robbie S, Henderson R, Balaggan K, Viswanathan A, Holder GE, Stockman A, Tyler N, et al. Effect of gene therapy on visual function in Leber's congenital amaurosis. N Engl J Med. 2008;358(21):2231–9. Hauswirth WW, Aleman TS, Kaushal S, Cideciyan AV, Schwartz SB, Wang L, Conlon TJ, Boye SL, Flotte TR, Byrne BJ, et al. Treatment of leber congenital amaurosis due to RPE65 mutations by ocular subretinal injection of adeno-associated virus gene vector: short-term results of a phase I trial. Hum Gene Ther. 2008;19(10):979–90. Maguire AM, Simonelli F, Pierce EA, Pugh EN Jr, Mingozzi F, Bennicelli J, Banfi S, Marshall KA, Testa F, Surace EM, et al. Safety and efficacy of gene transfer for Leber's congenital amaurosis. N Engl J Med. 2008;358(21):2240–8. den Hollander AI, Roepman R, Koenekoop RK, Cremers FP. Leber congenital amaurosis: genes, proteins and disease mechanisms. Prog Retin Eye Res. 2008;27(4):391–419. Thompson DA, Gyürüs P, Fleischer LL, et al. Genetics and phenotypes of RPE65 mutations in inherited retinal degeneration. Invest Ophthalmol Vis Sci. 2000;41(13):4293–9. Chung DC, Bertelsen M, Lorenz B, et al. The natural history of inherited retinal dystrophy due to biallelic mutations in the RPE65 gene. Am J Ophthalmol. 2019;199:58–70. Kumaran N, Georgiou M, Bainbridge JW, et al. Retinal structure in RPE65-associated retinal dystrophy. Investig Ophthalmol Vis Sci. 2020;61(4):47. Kumaran N, Rubin GS, Kalitzeos A, et al. A cross-sectional and longitudinal study of retinal sensitivity in RPE65-associated Leber congenital amaurosis. Investig Ophthalmol Vis Sci. 2018;59(8):3330–9. Hull S, Holder GE, Robson AG, et al. Preserved visual function in retinal dystrophy due to hypomorphic RPE65 mutations. Br J Ophthalmol. 2016;100(11):1499–505. Lorenz B, Poliakov E, Schambeck M, Friedburg C, Preising MN, Redmond TM. A comprehensive clinical and biochemical functional study of a novel RPE65 hypomorphic mutation. Investig Ophthalmol Vis Sci. 2008;49(12):5235–42. Rodrigues GA, Shalaev E, Karami TK, Cunningham J, Slater NKH, Rivers HM. Pharmaceutical development of AAV-based gene therapy products for the eye. Pharm Res. 2018;36(2):29. Acland GM, Aguirre GD, Bennett J, et al. Long-term restoration of rod and cone vision by single dose rAAV-mediated gene transfer to the retina in a canine model of childhood blindness. Mol Ther. 2005;12(6):1072–82. Acland GM, Aguirre GD, Ray J, et al. Gene therapy restores vision in a canine model of childhood blindness. Nat Genet. 2001;28(1):92–5. Bennicelli J, Wright JF, Komaromy A, et al. Reversal of blindness in animal models of leber congenital amaurosis using optimized AAV2-mediated gene transfer. Mol Ther. 2008;16(3):458–65. Ashtari M, Cyckowski LL, Monroe JF, et al. The human visual cortex responds to gene therapy-mediated recovery of retinal function. J Clin Investig. 2011;121(6):2160–8. Ashtari M, Nikonova ES, Marshall KA, et al. The role of the human visual cortex in assessment of the long-term durability of retinal gene therapy in follow-on RPE65 clinical trial patients. Ophthalmology. 2017;124(6):873–83. Ashtari M, Zhang H, Cook PA, et al. Plasticity of the human visual system after retinal gene therapy in patients with Leber’s congenital amaurosis. Sci Transl Med. 2015;7(296):296. Bainbridge JW, Mehat MS, Sundaram V, et al. Long-term effect of gene therapy on Leber’s congenital amaurosis. N Engl J Med. 2015;372(20):1887–97. Bainbridge JW, Smith AJ, Barker SS, et al. Effect of gene therapy on visual function in Leber’s congenital amaurosis. N Engl J Med. 2008;358(21):2231–9. Bennett J, Wellman J, Marshall KA, et al. Safety and durability of effect of contralateral-eye administration of AAV2 gene therapy in patients with childhood-onset blindness caused by RPE65 mutations: a follow-on phase 1 trial. Lancet. 2016;388(10045):661–72. Hauswirth WW, Aleman TS, Kaushal S, et al. Treatment of leber congenital amaurosis due to RPE65 mutations by ocular subretinal injection of adeno-associated virus gene vector: short-term results of a phase I trial. Hum Gene Ther. 2008;19(10):979–90. Maguire AM, High KA, Auricchio A, et al. Age-dependent effects of RPE65 gene therapy for Leber’s congenital amaurosis: a phase 1 dose-escalation trial. Lancet. 2009;374(9701):1597–605. Maguire AM, Russell S, Wellman JA, et al. Efficacy, safety, and durability of voretigene neparvovec-rzyl in RPE65 mutation-associated inherited retinal dystrophy: results of phase 1 and 3 trials. Ophthalmology. 2019;126(9):1273–85. Maguire AM, Simonelli F, Pierce EA, et al. Safety and efficacy of gene transfer for Leber’s congenital amaurosis. 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MalaCards is an integrated database of human maladies and their annotations, modeled on the architecture and richness of the popular GeneCards database of human genes. The MalaCards disease and disorders database is organized into "disease cards", each integrating prioritized information, and listing numerous known aliases for each disease, along with a variety of annotations, as well as inter-disease connections, empowered by the GeneCards relational database, searches, and GeneAnalytics set-analyses. Annotations include: symptoms, drugs, articles, genes, clinical trials, related diseases/disorders and more. An automatic computational information retrieval engine populates the disease cards, using remote data, as well as information gleaned using the GeneCards platform to compile the disease database. The MalaCards disease database integrates both specialized and general disease lists, including rare diseases, genetic diseases, complex disorders and more. On this site, you can search for ' retinitis pigmentosa ', and see the following: Picture description: Above picture is a sample MalaCard. MedlinePlus Genetics : 42 Retinitis pigmentosa is a group of related eye disorders that cause progressive vision loss. These disorders affect the retina, which is the layer of light-sensitive tissue at the back of the eye. In people with retinitis pigmentosa, vision loss occurs as the light-sensing cells of the retina gradually deteriorate.The first sign of retinitis pigmentosa is usually a loss of night vision, which becomes apparent in childhood. Problems with night vision can make it difficult to navigate in low light. Later, the disease causes blind spots to develop in the side (peripheral) vision. Over time, these blind spots merge to produce tunnel vision. The disease progresses over years or decades to affect central vision, which is needed for detailed tasks such as reading, driving, and recognizing faces. In adulthood, many people with retinitispigmentosa become legally blind.The signs and symptoms of retinitis pigmentosa are most often limited to vision loss. When the disorder occurs by itself, it is described as nonsyndromic. Researchers have identified several major types of nonsyndromic retinitis pigmentosa, which are usually distinguished by their pattern of inheritance: autosomal dominant, autosomal recessive, or X-linked.Less commonly, retinitis pigmentosa occurs as part of syndromes that affect other organs and tissues in the body. These forms of the disease are described as syndromic. The most common form of syndromic retinitis pigmentosa is Usher syndrome, which is characterized by the combination of vision loss and hearing loss beginning early in life. Retinitis pigmentosa is also a feature of several other genetic syndromes, including Bardet-Biedl syndrome; Refsum disease; and neuropathy, ataxia, and retinitis pigmentosa (NARP). MalaCards based summary : Retinitis Pigmentosa, also known as rp , is related to cone-rod dystrophy 2 and usher syndrome . An important gene associated with RetinitisPigmentosa is CRX (Cone-Rod Homeobox), and among its related pathways/superpathways are Metabolism of fat-soluble vitamins and The phototransduction cascade . The drugs Tocopherol and Vitamin A have been mentioned in the context of this disorder. Affiliated tissues include Eye , and related phenotypes are intellectual disability and nystagmus Click here to read more.