ICD-11 definition : Classical phenylketonuria is a severe form of phenylketonuria (PKU, ) an inborn error
of amino acid metabolism characterized in untreated patients by severe intellectual
deficit and neuropsychiatric complications.;
Classical phenylketonuria is a severe form of phenylketonuria (PKU, ) an inborn error
of amino acid metabolism characterized in untreated patients by severe intellectual
deficit and neuropsychiatric complications.