PHENYLKETONURIA AND THE MATERNAL PHENYLKETONURIA SYNDROME

Phenylketonuria is an inherited, autosomal recessive deficiency of hep atic phenylalanine hydroxylase activity. In affected individuals it is manifest as hyperphenylalaninemia which, if not controlled, limits co gnitive and neurological development. In pregnancy complicated by mate rnal phenylketonuria, the developing fetus is placed at increased risk of miscarriage or being affected by the maternal phenylketonuria synd rome; a syndrome associated with intrauterine growth restriction, micr ocephaly and cardiac malformation. Postnatal features include growth f ailure, cognitive impairment, cerebral palsy and epilepsy. These adver se effects occur regardless of whether the fetus itself does or does n ot have phenylketonuria. In pregnancy complicated by maternal phenylke tonuria it is possible to reduce the fetal risks by dietary restrictio n of phenylalanine. Indeed, strong reassurance regarding the lack of a dverse feta I effect from the maternal condition may be given if mater nal serum phenylalanine levels are stabilized to within normal or near -normal range, prior to and for the duration of pregnancy. A multidisc iplinary approach to preconception and antenatal care is therefore req uired in order to optimize obstetric outcome.