HUMAN AND MURINE PTX1 PTX1 GENE MAPS TO THE REGION FOR TREACHER-COLLINS-SYNDROME/

Ptx1 belongs to an expanding family of bicoid-related vertebrate homeo box genes. These genes, like their Drosophila homolog, seem to play a role in the development of anterior structures and, in particular, the brain and facies. We report the chromosomal localization of mouse Ptx 1, and the cloning, sequencing, and chromosomal localization of the hu man homolog PTX1. The putative encoded proteins share 100% homology in the homeodomain and are 88% and 97% conserved in the N- and C-termini respectively. Intron/exon boundaries are also conserved. Murine Ptx1 was localized, by interspecific backcrossing, to Chr 13 within 2.6 cM of Caml. The gene resides centrally on Chromosome (Chr) 13 in a region syntenic with human Chr 5q. Subsequent analysis by fluorescent in sit u hybridization places the human gene, PTX1, on 5q31, a region associa ted with Treacher Collins Franceschetti Syndrome. Taken together with the craniofacial expression pattern of Ptx1 during early development, the localization of the gene in this chromosomal area is consistent wi th an involvement in Treacher Collins Franceschetti Syndrome.