CLINICAL-FEATURES AND MOLECULAR-GENETIC ANALYSIS OF A BOY WITH PRADER-WILLI-SYNDROME CAUSED BY AN IMPRINTING DEFECT

Prader-Willi syndrome (PWS) is a neuroendocrine disorder caused by a n on-functioning paternally derived gene(s) within the chromosome region 15q11-q13. Most cases result from microscopically visible deletions o f paternal origin, or maternal uniparental disomy of chromosome 15. In both instances no recurrence has been reported. In rare cases, PWS is associated with lack of gene expression from the paternal allele due to an imprinting defect. We report the clinical features and the molec ular genetic analysis of the first Danish child with PWS due to a defe ct of the putative imprinting centre (IC). When the imprinting mutatio n is inherited from a carrier father, the risk that future children wi ll be affected is theoretically 50%. It is therefore important that th ese families are referred to a geneticist for counselling and further investigation. Prenatal diagnosis is currently only feasible when the mutation has been identified in the affected child.