DELETION INVOLVING D15S113 IN A MOTHER AND SON WITHOUT ANGELMAN-SYNDROME - REFINEMENT OF THE ANGELMAN-SYNDROME CRITICAL DELETION REGION

Deletions of 15q11-q13 typically resultin Angelman syndrome when inher ited from the mother and Prader-Willi syndrome when inherited from the father. The critical deletion region for Angelman syndrome has recent ly been restricted by a report of an Angelman syndrome patient with a deletion spanning less than 200 kb around the D15S113 locus. We report here on a mother and son with a deletion of chromosome 15 that includ es the D15S113 locus. The son has mild to moderate mental retardation and minor anomalies, while the mother has a borderline intellectual de ficit and slightly downslanting palpebral fissures. Neither patient ha s the seizures, excessive laughter and hand clapping, ataxia or the fa cial anomalies which are characteristic of Angelman syndrome. The prox imal boundary of the deletion in our patients lies between the D15S10 and the D15S113 loci. Our patients do not have Angelman syndrome, desp ite the deletion of the D15S113 marker. This suggests that the Angelma n syndrome critical deletion region is now defined as the overlap betw een the deletion found in the previously reported Angelman syndrome pa tient and the region that is intact in our patients. (C) 1995 Wiley-Li ss, Inc.