Early diagnosis is critical for improving prognosis with interventions and treatments. With current medical knowledge and the availability of molecular testing, most cases are diagnosed during early infancy. If screening with the most recent clinical diagnostic criteria (in bold type below) raises a diagnostic suspicion of PWS, this should prompt DNA testing and a methylation analysis test will detect PWS in over 99% of cases. PWS equally affects males, females and all ethnicities. Birth incidence estimates vary – the PWSA(NZ) uses 1 in 16,000 based on mean study data.
Clinical symptoms in infants
If clinical findings prompt molecular genetic testing, DNA methylation analysis is recommended. This is the only test that will diagnose PWS caused by all three genetic mechanisms: paternal deletion, maternal uniparental disomy (UPD) 15 and imprinting defect (ID). View this flow chart demonstrating a testing strategy for determining the genetic mechanism in an individual with PWS. (Prader-Willi Syndrome: Driscoll, Miller, Schwartz and Cassidy, revised 2017)