progressive retinal atrophy (PRA). Because research has been extensive for human blindness, we can use this information to improve the health of felines. Our goal is to investigate the progression of an inherited blindness in Persians and decipher which gene results in the disease. Persian cats are the most popular cat breed throughout the world. Many other breeds use Persians to change the body and facial structures of other breeds as allowable outcrosses. Thus, health problems in Persians can be spread quickly and widely in the cat world if unchecked. The Persian vision problems start very early, at about 4 – 8 weeks of age and progress very rapidly. Cats become completely blind by 15 weeks of age, but do not have other health issues. This disease is caused by a mutation in one gene and two copies of that mutation are required to cause blindness. Carrier cats, cats with one copy of the mutation, are perfectly healthy, but when bred, they can pass the mutation on to their offspring. Thus, a genetic test is required to detect these cats so that they do not spread the mutation. The disease has to be clinically very well defined in order to match this disease to one that is found in humans. If a good match can be made, then markers for that gene can be developed for the cat rather efficiently and used to detect carriers. Also, if we know which gene is mutated, we may understand how the genes function and be able to give better medications to slow or stop the blindness. A chromosomal segment has been recently identified that is statistically associated with the Persian form of PRA. It is most likely that a gene within the segment is responsible for the Persian blindness and a mutation test will be feasible in the near future.