What we know that could influence future treatment of phenylketonuria

Summary Phenylketonuria (PKU), a Mendelian autosomal recessive phenotype (OMIM 261600), is an inborn error of metabolism that can result in impaired postnatal cognitive development. The phenotypic outcome is multifactorial in origin, based both in nature, the mutations in the gene encoding the l ‐phenylalanine hydroxylase enzyme, and nurture, the nutritional experience introducing l ‐phenylalanine into the diet. The PKU story contains many messages including a framework to appreciate the complexity of this disease where phenotype reflects both locus‐specific and genomic components. This knowledge is now being applied in the development of patient‐specific therapies.