A recessive genetic disorder that leads to functional deficits in children arising from a neurochemical deficit in the prefrontal cortex (i.e., the enzyme converting dietary phenylalanine to tyrosine is deficient, resulting in the excretion of phenylpyruvate, or phenylalanine, into the urine). While cognitive impairment is common and about 25% of cases have epileptic attacks, it can be detected soon after birth and treated with a low diet of phenylalanine.
See Guthrie test, Epilepsy