One of the following disorders is due to maternal disomy of chromosome 15-

Angelman syndrome, as might be expected, also can result from uniparental disomy of parental chromosome 15 Patients with the Angelman syndrome are born with a deletion of the same chromosomal region derived from their mothers. Patients with Angelman syndrome also are mentally retarded, but in addition they present with ataxic gait, seizures, and inappropriate laughter. Because of the laughter and ataxia, this syndrome has been called the happy puppet syndrome. (Robbins Basic Pathology,9th edition,pg no. 244)