Last updated January 24, 2021
Inherited retinal degenerations (IRDs), including retinitis pigmentosa (RP) refer to a heterogeneous group of Mendelian disorders caused by mutations in over 200 genes and resulting in vision loss due to loss of structure and function of rod and/or cone photoreceptors. Among the most common genetic causes of IRDs are mutations in the RPGR gene located on the X-chromosome; by far the majority of the RPGR mutations are located in the ORF15 exon of the gene. Most, but not all, patients with RPGR-ORF15 mutations are diagnosed with X-linked RP (XLRP). In addition to causing visual disability in humans, naturally-occurring mutations in ORF15 exon are also found in dogs and mice with retinal degeneration. The exact function of RPGR in the rod and cone photoreceptors remains poorly understood but it is suggested to be involved in regulating ciliary transport. Successful experiments in gene augmentation therapy at different disease stages of dogs with RPGR-ORF15 mutations have set a clear path for clinical trials of gene augmentation therapy in patients.
Cideciyan Lab has been involved with better understanding and potentially treating XLRP for over 25 years. Our work includes details of disease expression in hemizygous male patients and heterozygous female carriers (See refs using below link: 2,3,7,9,21,24,85,90,127,166), as well as understanding of retinal disease features in mice (127,168) and dogs (126,137,142,154,176). More recently, the lab has been concentrating on gene augmentation therapy applied to dogs with RPGR-ORF15 mutations (126,142,154,176,206,210), specific disease features in patients in order to determine when and where to treat, and what outcomes to use (168,194), and hypotheses based on RPGR isoform imbalance in different ORF15 mutations (215).