First arch malformation: a new craniofacial mutant in the mouse.

The first arch malformation arising in a BALB/c strain of mice, has been shown to be inherited as a single autosomal recessive gene and is given the provisional gene symbol far. Affected newborns have extensive bony defects of the face and skull, including a cleft secondary palate, and die within 24 hours of birth. Most of the abnormalities occur in bones derived from the first branchial arch and most of the bony derivatives of the first arch are abnormal in the mutant.