De novo direct duplication of 15q15-->q24 in a newborn boy with mild manifestations.

Duplication of distal 15q results in a recognizable clinical phenotype. We report here on a 25-day-old boy with a de novo interstitial duplication of chromosome region 15q15-q24. The manifestations in this patient are milder than those of previously described patients and include minor facial anomalies, velopharyngeal insufficiency, branchial cleft cyst, and hydronephrosis. Fluorescence in situ hybridization (FISH) using a chromosome 15 painting probe confirmed that the extra material is of chromosome 15 origin. Further analysis with the SNRPN probe demonstrated that the duplication is telomeric to the Prader-Willi/Angelman syndrome critical region. This case delineates a broader spectrum for patients with duplication 15q syndrome.