Individuals with phenylketonuria have profound and irreversible intellectual disability,microcepgaly,epilepsy and behavioral problems.These patients often have a musty body odour and skin conditions such as eczema caused by excretion of excessive phenylalanine and its metabolites.Decreased skin hair, and eye pigmentation may also be present due to reduced melanin synthesis.Ferric chloride test will be positive due to the presence of phenols,which are its metabolites. Reference:Essential pediatrics-Ghai,8th edition,page no:652