Universal screening for phenylketonuria, which has an estimated prevalence of one per 10,000 to one per 12,000 live births, is recommended for newborns in the U.S.11 When phenylketonuria prevalence is compared with that of congenital LQTS (one in 2,000-2,500 live births), it would appear reasonable to adopt universal screening for LQTS. However, factors other than prevalence???like the sensitivity