Proximal duplications of chromosome 15: clinical dilemmas.

The apparently rare cytogenetic abnormality of partial trisomy 15 was diagnosed by the authors in a patient presenting with developmental retardation, macrocephaly with ventricular enlargement and prominent subarachnoid spaces, hypotonia, low-set ears, hyperextensible wrists and hands, high arched palate, tapering fingers, right esotropia, and bilateral metatarsus adductus. Clinical findings in this case are similar to previously reported cases of proximal duplications of chromosome 15 and bear some similarity to the Prader-Willi syndrome. However, our patient did not have the severe hypotonia, early failure to thrive, or genital abnormalities seen in classical Prader-Willi syndrome. This case supports the theory that a variety of cytogenetic aberrations in proximal 15q can cause a "Prader-Willi-like" syndrome. Increased clinical suspicion is needed when patients are seen with hypotonia, retarded development and mild dysmorphism if the variety of phenotypes are to be delineated.