Retinal atrophy, progressive (Bengal, PRA-b)

 

Gene: KIF3B

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, KIF3B gene; c.1000G>A, p.(A334T), exon 1, cat chromosome A3.

Medical system: Ocular

Breeds: Bengal, Savannah

Age of onset of symptoms: 9 to 20 weeks for visible changes with an ophthalmologic exam, 1 year to see changes in behavior due to loss of vision.

Progressive retinal atrophy in the Bengal is a relatively breed-specific disease that causes a progressive loss of light-sensitive receptors (cones and rods) in the eye. The animal loses its vision, until reaching blindness, on average by the age of two years, but the condition progresses at a different rate in each cat.  The first observable clinical signs include difficulties in orientation at night, an increase in vocalizations and a stronger attachment to the owner. In addition, the pupils may be more dilated than in a normal animal under the same light conditions and the vibrissae (whiskers) may be carried more pronouncedly forward.  As the disease progresses, an increase in the reflectivity of the back of the eye (hyper reflectivity of the tapetum lucidum) may be seen. The definitive diagnosis will be made by a veterinarian following an ophthalmic examination.  DNA tests to reveal the presence of the mutation are available.

It should be noted that the Progressive retinal atrophy, late onset blindness (PRA-rdAc) seen in numerous cat breeds is the result of a mutation in a separate gene.

 

References:

OMIA link: [2267-9685]

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]

Cogné B, Latypova X, Senaratne LDS, et al. (2020) Mutations in the kinesin-2 motor KIF3B cause an autosomal-dominant ciliopathy. Am J Hum Genet 106:893-904.  [pm/32386558]

Ofri R, Reilly CM, Maggs DJ, et al. (2015) Characterization of an Early-Onset, Autosomal Recessive, Progressive Retinal Degeneration in Bengal Cats. Invest Ophthalmol & Vis Sci, 56(9):5299-5308.  [pubmed/26258614]

 

Contributed by: Gilbert Kirouac and Laurence Banville, Class of 2027, Faculté de médecine vétérinaire, Université de Montréal.   (Translation DWS).

Update by : Laury-Ann Giasson et Sofia Ostrioglo, class of 2028, Faculté de médecine vétérinaire, Université de Montréal.