Cats with Burmese Head Defect, also known as frontonasal dysplasia, are born with severe craniofacial defects making them unviable and requiring euthanasia soon after birth. The defect is characterized by the absence of a visible nose, protrusion of the meninges and brain through the cranium, abnormal development of the maxillary processes, and ocular degeneration. This severe defect is caused by inheriting two copies of the gene mutation. However, inheriting one copy of the mutation causes the cat to have the desired brachycephalic appearance seen in several breeds. Thus, the inheritance pattern is considered codominant.

Kittens exhibiting the severe form of the disorder at birth are typically humanely euthanized due to welfare concerns.

There are many responsibilities to consider when breeding cats. Regardless of test results it is important that your cat is in good general health and that you are in a position to care for the kittens if new responsible owners are not found. For first time or novice breeders, advice can be found at most cat registry websites.

This genetic mutation follows an autosomal dominant mode of inheritance. Cats with one copy show the breed desired shortened face and muzzle (brachycephaly), while cats with two copies show severe craniofacial malformation. As one copy of the mutation produces cats with brachycephaly, it is advised to only breed carrier cats with one copy of the Burmese Head Defect mutation to clear cats with no copies of the Burmese Head Defect mutation. About half of the kittens will have one copy of the Burmese Head Defect mutation and half will have no copies of the Burmese Head Defect mutation. This will decrease the likelihood of kittens in the litter developing the severe form of the disease. Carrier to carrier matings are not advised as the resulting litter will likely contain kittens with two copies of the Burmese Head Defect mutation and these kittens are likely to develop the severe form of the disease. Suspected carriers should be tested prior to breeding. Please note: It is possible that disease signs similar to the ones caused by the Burmese Head Defect mutation could develop due to a different genetic or clinical cause.