ISOLATION AND CHARACTERIZATION OF A MAGE GENE FAMILY IN THE XP21.3 REGION

A human gene with strong homology to the MAGE gene family located in X qZ7-qter has been isolated by using exon-trapping of cosmids in the Xp 21.3 region. We have mapped and sequenced cDNA and genomic clones corr esponding to this gene, MAGE-Xp, and shown that the last exon contains the open reading frame and is present in a minimum of five copies in a 30-kb interval, MAGE-Xp, is expressed only in testis and, unlike the Xq27-qter MAGE genes, it is not expressed in any of 12 different tumo r tissues tested. However, the gene and predicted protein structure ar e conserved, suggesting a similar function, MAGE-Xp is located in the 160-kb critical interval defined for the locus involved in sex determi nation within Xp21 and is 50 kb distal to the DAX-1 gene, which is res ponsible for X-chromosome-linked adrenal hypoplasia congenita.