Prader-Willi and Angelman Syndromes: Discrepancy between clinical and laboratory diagnoses

Prader-Willi syndrome (PWS) and Angelman syndrome (AS) are distinct mental retardation disorders and they are both determined by the uniparental contribution (cytogenetic deletion or uniparental disomy) to the 15q11-q13 region that is under the control of genomic imprinting The PWS and AS clinical diagnosis must be confirmed by a two step laboratory approach: the methylation test to determine the uniparental contribution and eventually followed by the FISH to detect the cytogenetic deletion. We present the results of our analysis on 48 patients (31 suspected PWS, 17 suspected AS) and report the international diagnostic criteria for these two syndromes.