Retinopathy
Gene: RDH5
Transmission: Autosomal recessive
For an autosomal recessive genetic disease, an animal must have two copies of the mutation in question to be at risk of developing the disease. Both parents of an affected animal must be carriers of at least one copy of the mutation. Animals that have only one copy of the mutation are not at risk of developing the disease but are carrier animals that can pass the mutation on to future generations.
Mutation: Substitution, RDH5 gene; c.542 G>T, p.(G181V), chr.B4.
Medical system: Oculaire
Breeds: Domestic Cat
Age of onset of symptoms: From 5 months to more that 2.5 years
Retinal degeneration was observed in a single domestic cat within a research colony, and through backcross breeding a pedigree was developed to study the phenotype. Affected cats showed poor adaptation to night vision (night blindness). In addition, they had retinal thinning with degeneration of the area centralis (equivalent to the human macula) due to rod cell destruction. Genomic studies performed on two affected and one obligate carrier animals revealed a mutation within the RDH5 gene as the probable cause of the phenotype retinal degeneration phenotype. The RDH5 gene codes for the retinol dehydrogenase 5 enzyme, involved in the recycling of photoreceptor visual pigments. Further studies of the diseased pedigree supported an autosomal recessive mode of inheritance. It was suggested that modifying genes acting in concert with the RDH5 mutation are responsible for the wide variation observed for the onset of clinical signs between affected cats. It is to be noted that this mutation and phenotype were observed in a closed research colony of cats, and that no survey studies of mutation frequencies are reported for domestic cats in general or for purebred cats in particular. Although certainly of academic interest, the reported mutation of the RDH5 gene does not appear to be of clinical concern for domestic or purebred cat populations.
References:
OMIA link: [2469-9685]
Occelli LM, Daruwalla A, De Silva SR, et al. (2021) A large animal model of RDH5-associated retinopathy recapitulates important features of the human phenotype. Hum Mol Genet 31(8):1263-1277. [pm/34726233]
Contributed by: Gabrielle Raymond and Célia Deconinck-Vandevoorde, Class of 2028, Faculty of Veterinary Medicine, University of Montreal. (Translation DWS).