The neonatal presentation of Prader-Willi syndrome revisited.

We describe 6 newborns evaluated for hypotonia, later diagnosed with Prader-Willi syndrome despite the absence of the classical neonatal features of this syndrome. Specific genetic testing for Prader-Willi syndrome should be considered for all neonates with undiagnosed central hypotonia even in the absence of the other major features of this syndrome.