Retinal atrophy, progressive (Early-onset blindness, PRA-Rdy)

 

Gene: CRX

Transmission: Autosomal dominant (incomplete)

For a genetic disease that is autosomal dominant, the animal only has to have one copy of the mutation in question to be at risk of developing the disease.  Animals with two copies of the mutation generally have more severe symptoms and an earlier onset of the disease than animals with just one copy of the mutation.  Offspring are potentially at risk of developing the disease if at least one parent carries the mutation.

Mutation: Deletion, CRX gene; c.546 del.C, p.(P185L fs STOP 2), exon4

Medical system: Ocular

Breeds: Abyssinian, Somali

Age of onset of symptoms: 2 weeks of age

PRA-Rdy is a genetic disease of the photoreceptor cells of the retina that has been documented in Abyssinian cats.  The disease is caused by abnormal (retarded) development of the photoreceptor cells, followed by their degeneration.  First signs of the disease occur by 2 weeks of age, and involve dilated pupils and slowed light reflexes.  Retinal changes can be observed in affected eyes by 8 to 12 weeks, and at this time the kitten is effectively blind.  PRA-Rdy is a rare disease and because it is transmitted with autosomal dominant heredity, it is essentially self-limiting.

 

References:

OMIA link: [0881-9685]

Occelli LM, Jones BW, Cervantes TJ, Petersen-Jones SM. (2023) Metabolic changes and retinal remodeling in Heterozygous CRX mutant cats (CRX RDY/+). Exp Eye Res :109630.  [pubmed/37625575]

Anderson H, Davison S, Lytle KM, et al. (2022) Genetic epidemiology of blood type, disease and trait variants, and genome-wide genetic diversity in over 11,000 domestic cats.  PLoS Genet. 16;18(6):e1009804.  [pubmed/35709088]

Menotti-Raymond M, Deckman KH, David V, et al. (2010) Mutation discovered in a feline model of human congenital retinal blinding disease.  Biochemistry and Molecular Biology 51(6):2852-2859. [pubmed/20053974]