Duplication of chromosome 15 in the region 15q11-13 in a patient with developmental delay and ataxia with similarities to Angelman syndrome.

Duplications of the proximal long arm of chromosome 15 have been seen in the Prader-Willi syndrome (PWS), and in subjects without the Prader-Willi phenotype but with other clinical features including short stature, diabetes, anal and jejunal atresia, and acanthosis nigricans. The non-PWS subjects all had different phenotypes despite the identical findings on cytogenetic analysis. A normal phenotype has also been observed in patients with similar duplications. We report a further patient with a duplication of 15q11-13 which was detected cytogenetically and confirmed on molecular genetic analysis. She has developmental delay, particularly concerning the acquisition of speech, and an ataxic gait. These are interesting clinical features in view of the association of Angelman syndrome with abnormalities of 15q11-13.