A YAC contig has been constructed spanning 1.1 Mb of human chromosome band 10q11.2 which encompasses three markers (D10S141, RET, D10S94) closely linked to the gene for MEN 2A. This physical linkage group is ordered cen-D10S141-RET-D10S94-qter, and must include MEN2A, which lies in a 480 kb region between flanking markers D10S141 and D10S94.