Normal dosage of the insulin and insulin-like growth factor II genes in patients with the Beckwith-Wiedemann syndrome.

Several patients in whom the Beckwith-Wiedemann syndrome (BWS) is associated with duplication of chromosomal region 11p15 have recently been observed. The genes encoding insulin and insulin-like growth factor II (IGF-II), proteins that affect cellular growth and pancreatic function, have been mapped to 11p15, and their increased expression might, thus, account for the physical features of BWS. To determine whether BWS is frequently associated with small duplications of 11p15, we performed dosage analyses of the insulin and IGF-II genes in somatic DNAs of seven patients with BWS. In each case, we observed apparent diploid representation of these genes. These data suggest that BWS is not frequently associated with small duplications of 11p15 material that embed the insulin and IGF-II genes.