Feline Progressive Retinal Atrophy (rdy-PRA)
Feline Progressive Retinal Atrophy (rdy-PRA) is an eye disorder or simply a form of blindness. It belongs to a group of inherited blinding feline diseases (PRA)that affect the retina of the eye. The retina is located at the back of the eye, and contains rods and cones, which are specialised cells thar are essential for vision. PRA is seen in many pure breeds, although the exact genetic cause is known for only a few. An early-onset rod–cone dysplasia (Rdy) was first described in a domestic cat of the Abyssinian breed in the United Kingdom. The disorder also affects Somali and Ocicat breeds.
Characteristics and Symptoms
In feline progressive retinal atrophy (rdy-PRA) abnormal photoreceptor development is observed first at 22 days of age, with older individuals displaying more advanced photoreceptor degeneration and thinning of the neural retina. Rdy-affected cats display retarded development of the photoreceptor cells, followed by degeneration when these cells initiate functional differentiation. The disease causes loss of vision by the time a cat reaches 12-16 months of age.
Feline progressive retinal atrophy (rdy-PRA) is caused by a mutation in CRX gene. The CRX gene is a member of the protein family that is requisite for mammalian eye development. The disorder is inherited in autosomal dominant manner. That means that both cats carrying one copy of mutated gene (heterozygous cats) and cats carrying two copies of mutated gene (homozygotes for the mutation) show signs of the disease. With a DNA test for feline progressive retinal atrophy (rdy-PRA) affected heterozygotes can be differentiated from affected homozygotes which is important for future breeding and preventing of spreading the mutation in the population.