Inherited homeotic midfacial malformations in Burmese cats.

During the past three decades, Burmese cats have been selected for a shorter muzzle and a more rounded face. Recently there arose a line of these animals that consistently exhibit such a brachycephalic appearance; unfortunately, approximately 25% of these kittens are born with a neonatal lethal midfacial malformation. The abnormality is characterized by agenesis of all derivatives of the medial nasal prominence; lateral duplication of most derivatives of the maxillary process; including the canine teeth and whiskers fields; telencephalic meningoencephalocele; and secondary ocular degeneration. The anatomy, embryology, and pattern of inheritance of this unique midfacial malformation are described.