Hypotrichosis is a genetic disorder affecting the Birman cat breed. Affected kittens are either born bald or have a thin downy coat that falls out within a week of birth. Some kittens are dead at birth. Affected kittens may grow a thin coat within the first two months while others remain bald. The immune system does not function properly. Most kittens succumb to infections and usually die within 13 weeks of birth.
Other clinical signs include greasy skin and crusting of the skin around the face from where the mother has tried to groom them. Often more than one animal is affected per litter. Other abnormalities described in affected Birman cats include absence of whiskers and claws and abnormalities on the surface of the tongue.