Assignment of the canine paired-box 3 (PAX3) gene to chromosome 37q16-->q17 by in situ hybridization.

PAX3 belongs to a family of developmental control genes that encode nuclear transcription factors. Their characteristic domain (paired domain) is a conserved amino acid motif with DNA-binding activity. During development PAX3 is expressed in the dorsal neural tube and the developing somite and is necessary for the formation of caudal neural crest derivatives and the migration of myoblasts into the limb (Terzic and Saraga-Babic, 1999). Mutations in the human PAX3 gene have been associated with Waardenburg syndrome (WS) type I and type III. In mice mutations in the Pax3 gene cause a phenotype known as splotch. WS I and splotch mutations change the DNA-binding properties of the protein or the ability to build up homodimers (Tassabehji et al., 1992; Chalepakis et al., 1994). Focusing on the importance of PAX genes in development we performed FISH analysis to determine the chromosomal location of PAX3 in the canine genome (Fig. 1).