This article is from the Korats Breed FAQ, by Dennis Ganoe firstname.lastname@example.org with numerous contributions by others.
Korats are not prone to any particular illnesses. However, there have
been rare instances of a genetic neuromuscular degenerative
disease that has been identified in the Korat as well as other
breeds of cats, called GM1 Gangliosidosis and GM2 Gangliosidosis.
The symptoms of this disease normally appear before the kittens
are four months old, therefore most Korat owners would never know
that it exists. The kittens that are not affected show no outward
signs even if they were a carrier, and they live normal and
healthy lives. Only in a breeding situation should this be of any
concern. Since this is caused by a recessive gene, parents that
produce affected kittens should be taken out of the breeding
program. A blood test exists at present for the disease but is not
widely available because it is presently experimental. Perhaps in
the future it will be more widely available.