Abstract
The Prader—Willi syndrome and the Angelman syndrome are caused by the loss of function of distinct but closely linked genes on human chromosome 15. Based on a yeast artificial chromosome restriction map and two key patients we have determined that the shortest region of deletion overlap in the Prader—Willi syndrome comprises 320 kb. The region Includes the anonymous DNA marker PW71 (D15S63) and the gene for the small nuclear ribonucleoprotein N (SNRPN). The SNRPN gene maps 130 kb distal to PW71 and is transcribed from centromere to telomere