Dehydratase deficiency or pterin-4 alpha-carbinolamine dehydratase (PCD) is considered a transient and benign form of hyperphenylalaninemia due to tetrahydrobiopterin deficiency (see this term), characterized by muscular hypotonia, irritability (detected by EEG), slow acquisition of psychomotor skills, age-dependent movement disorders, including dystonia and an accompanying excretion of 7-substituted pterins. Neurological developement is normal with dietary control of blood phenyalanine. PCD is inherited in an autosomal recessive manner. The disease is Dehydratase deficiency (Orphanet_1578, an Orphanet rare-disease nomenclature identifier). Also known as: CADH deficiency, Hyperphenylalaninemia due to dehydratase deficiency, Hyperphenylalaninemia due to pterin-4-alpha-carbinolamine dehydratase deficiency, Hyperphenylalaninemia with primapterinuria, PCBD deficiency.