GCH1, Official Symbol GCH1provided by HGNC Official Full Name GTP cyclohydrolase 1provided by HGNC Primary source HGNC:HGNC:4193 See related Ensembl:ENSG00000131979 MIM:600225; AllianceGenome:HGNC:4193 Gene type protein coding RefSeq status REVIEWED Organism Homo sapiens Lineage Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo Also known as GCH; DYT5; DYT14; DYT5a; GTPCH1; HPABH4B; GTP-CH-1 Summary This gene 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. [provided by RefSeq, Jul 2008] Expression Broad expression in liver (RPKM 22.0), bone marrow (RPKM 9.4) and 19 other tissues See more Orthologs mouse all