Duplication or insertion in 15q11–13 associated with mental retardation ‐short stature and obesity ‐ Prader‐Willi or Cohen syndrome?

Abstract
Difficulties of differential diagnosis between Prader‐Willi Syndrome and Cohen Syndrome are demonstrated in a 12–year‐old girl with obesity and mental retardation.Cytogenetic studies showed an apparently supernumerary band on chromosome 15 in the proximal region q11‐13.Both parents have a normal karyotype.The aberrant chromosome was derived from an apparently normal paternal chromosome.