Discontinuation of Pegvaliase therapy during maternal PKU pregnancy and postnatal breastfeeding: A case report

摘要

Phenylketonuria (PKU) is an inherited metabolic disorder due tophenylalanine hydroxylase (PAH) deficiency resulting in an elevation ofPhe [1]. High blood phenylalanine (Phe) is associated with developmental disability, seizures and eczema that are prevented if blood Phe iscontrolled from infancy within 120–360 μmol/L [2]. The primarytreatment for PKU is a Phe-restricted diet that eliminates high proteinfood and relies on the use of low or Phe-free medical foods. The diet isdifficult to follow, and this results in sub-optimal blood Phe, especiallyin adults [3], with associated adverse neuropsychological outcomes [4].Consequently, additional non-dietary therapies have been developed.The first of these to be approved was saproterin dihydrochloride,1 asynthetic form of the PAH cofactor tetrahydrobiopterin (BH4). Inpharmacological amounts this oral therapy usually serves as adjunctiveto diet by enhancing PAH activity in a subpopulation of those with PKU,thereby allowing for a degree of diet liberalization in those patients [5].A second and more recently approved therapy is pegvaliase pqpz1(pegvaliase), an injectable enzyme substitution therapy that convertsphenylalanine to trans-cinnamic acid and ammonia and can replacedietary therapy in those with PKU who respond to this treatment [6].