Phenylketonuria (PKU) is associated with deficient activity of phenylalanine hydroxylase (PAH).

Chromosome: 12q23.2

Protein: phenylalanine-4-hydroxylase


Criteria for diagnosis - one of the following:

(1) molecular testing to demonstrate biallelic pathogenic variants of PAH

(2) all of the following

(2a) persistent plasma phenylalanine concentration > 120 µmol/L (2 mg/dL)

(2b) increased ratio of phenylalanine to tyrosine ratio (> 3 versus normal < 1)

(2c) normal BH4 cofactor metabolism

To read more or access our algorithms and calculators, please log in or register.