A clinical, cytogenetic, andmolecular study of 40adults withthePrader-Willi syndrome

A clinical, cytogenetic, and molecular studyhasbeencarried outon 40adults withafirmdiagnosis ofPrader-Willi syndrome.A cytogenetically detectable deletion wasobserved in58%whilefurther subjects had a deletion whichwas detectable bymolecular methodsonly, giving a totalof76%.Fourcasesofmaternal uniparental disomy(UPD)wereallfemale.Threeofthemwereheterodisomic whilethefourth wasisodisomic. Twomale probandswereheterozygous atallloci tested yetdidnothaveUPD. Although methylation studies showedthatone of themhadasingle bandusing probePW71, theotheronehadtwobands.Psychiatric studies suggest thatfemales withmaternal UPD areindistinguishable psychologically fromthosewitha paternal deletion in 15qIIqI3.