This unmet need has been recognized by 2 previous studies that proposed utility of SNRPN promoter methylation as a first-tier test for PWS and/or AS newborn screening.14,15 These studies used a small number of samples from PWS and/or AS patients and controls, primarily focused on methods of DNA extraction from blood spots, but did not examine method feasibility at population scale or utility for detection of infants with Dup15q. Here, SNRPN is linked to Prader-Willi syndrome.