GCH1 encodes a member of the GTP cyclohydrolase family. The encoded protein is the first and rate-limiting enzyme in tetrahydrobiopterin (BH4) biosynthesis, catalyzing the conversion of GTP into 7,8-dihydroneopterin triphosphate. BH4 is an essential cofactor required by aromatic amino acid hydroxylases as well as nitric oxide synthases. Mutations in this gene are associated with malignant hyperphenylalaninemia and dopa-responsive dystonia. Several alternatively spliced transcript variants encoding different isoforms have been described; however, not all variants give rise to a functional enzyme.GCH1 (GTP Cyclohydrolase 1) is a Protein Coding gene. Diseases associated with GCH1 include Hyperphenylalaninemia, Bh4-Deficient, B and Dystonia, Dopa-Responsive, With Or Without Hyperphenylalaninemia. Among its related pathways are eNOS activation and regulation and Metabolism.
