Abstract

Progressive retinal atrophy (PRA) is an inherited blindness occurring across multiple mammalian taxa. Humans have over 25 characterized forms of PRA. Several forms of PRA have been described in cats, including an early-onset Persian PRA and a late-onset Abyssinian PRA. A novel mid-onset PRA has recently been reported in the Bengal cat breed. A nine-month male Bengal (proband) presented with tapetal hyperreflectivity at the UC Davis Veterinary Medicine Teaching Hospital. An ophthalmological exam revealed compromised vision, delayed dazzle and pupillary reflexes and bilateral retinal vessel degeneration. The proband was subsequently donated to UC Davis for test breeding. Additionally, breeders have performed repeated breedings to produce cats to confirm the mode of inheritance. Complementation test breedings of the proband with a PRA-affected Persian and a PRA-affected Somali (an Abyssinian-derived breed) were performed in order to ascertain whether the Bengal PRA results from mutations in the same genes as either of these previously described diseases. The progeny from these crosses indicate that the mid-onset PRA in the Bengal breed is a distinct novel PRA. An extended 46-member, nine-generation pedigree has been established. Mid-onset PRA in at least ten affected Bengals traces to a single common ancestor between three and six generations prior, and pedigree analysis suggests an autosomal recessive mode of inheritance. Sequence analysis confirmed that Bengal PRA is not caused by the mutation responsible for late-onset Abyssinian PRA. A breeding colony has been established, and the Bengal PRA will be histologically and clinically characterized. DNA samples provided by breeders, as well as from the breeding colony, will be used to genetically characterize this novel form of PRA in the Bengal breed.