Pterin-4 alpha-carbinolamine dehydratase 1 (PCBD1) deficiency is considered a transient and benign form of hyperphenylalaninemia due to tetrahydrobiopterin deficiency, 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 development is normal with dietary control of blood phenyalanine. PCBD1 is inherited in an autosomal recessive manner. The disease is pterin-4 alpha-carbinolamine dehydratase 1 deficiency (Monarch Disease Ontology term MONDO_0009908). Also known as: CADH deficiency, PCBD deficiency, PCBD1 deficiency, PCD deficiency, dehydratase deficiency, hyperphenylalaninemia due to dehydratase deficiency, hyperphenylalaninemia due to pterin-4-alpha-carbinolamine dehydratase deficiency, hyperphenylalaninemia with primapterinuria.