Phenylketonurias

**Definition:** A group of autosomal recessive disorders marked by a deficiency of the hepatic enzyme PHENYLALANINE HYDROXYLASE or less frequently by reduced activity of DIHYDROPTERIDINE REDUCTASE (i.e., atypical phenylketonuria). Classical phenylketonuria is caused by a severe deficiency of phenylalanine hydroxylase and presents in infancy with developmental delay; SEIZURES; skin HYPOPIGMENTATION; ECZEMA; and demyelination in the central nervous system. (From Adams et al., Principles of Neurology, 6th ed, p952).

**Tree numbers:** - C10.228.140.163.100.687 - C16.320.565.100.766 - C16.320.565.189.687 - C18.452.132.100.687 - C18.452.648.100.766 - C18.452.648.189.687

**Synonyms:** - Phenylketonuria