This site is intended for healthcare professionals

Go to /sign-in page

You can view 5 more pages before signing in

Clinical features

Last reviewed dd mmm yyyy. Last edited dd mmm yyyy

Authoring team

Children affected by this condition are normal at birth and in the neonatal period.

Developmental delay becomes apparent at about 3 months when the child fails to sit, walk, or talk at the appropriate times.

The IQ of untreated patients is usually under 50. Behavioural abnormalities and microencephaly is common, and seizures occur in about 25% of patients.

Other possible clinical features of the disease include light pigmentation, blue eyes, fair hair, eczema and mousy odour, unless treated by low phenylalanine diet.

Create an account to add page annotations

Add information to this page that would be handy to have on hand during a consultation, such as a web address or phone number. This information will always be displayed when you visit this page