Hyperphenylalaninemia

Hyperphenylalaninemia is an inborn error of amino acid metabolism characterized by persistent, abnormally elevated concentrations of phenylalanine in the blood

Hyperphenylalaninemia is an inborn error of amino acid metabolism characterized by persistent, abnormally elevated concentrations of phenylalanine in the blood It most commonly affects infants, children, and adults with pathogenic variants leading to deficiency of the hepatic enzyme phenylalanine hydroxylase (PAH), but it can also arise from defects in the synthesis or regeneration of its essential cofactor, tetrahydrobiopterin (BH4)

It most commonly affects infants, children, and adults with pathogenic variants leading to deficiency of the hepatic enzyme phenylalanine hydroxylase (PAH), but it can also arise from defects in the synthesis or regeneration of its essential cofactor, tetrahydrobiopterin (BH4) Impaired conversion of phenylalanine to tyrosine causes neurotoxic systemic accumulation that primarily impacts the central nervous system

Impaired conversion of phenylalanine to tyrosine causes neurotoxic systemic accumulation that primarily impacts the central nervous system

Impaired conversion of phenylalanine to tyrosine causes neurotoxic systemic accumulation that primarily impacts the central nervous system

Left unmanaged, severe forms such as classic phenylketonuria lead to progressive cognitive impairment, developmental delays, behavioral disturbances, microcephaly, and seizures, whereas milder variants may demonstrate fewer or no neurological sequelae