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Gene

GCH1

GTP cyclohydrolase 1

Summary

Cytogenetic location
14q22.2
Coordinates
Chromosome 14: 54,842,017–54,902,826 (GRCh38)
Exons
6 exons across 60.8 kb
Protein
250 amino acids
Inheritance
Autosomal recessive
Also known as
GTPCH1, DYT5a
Previous symbols
GCH, DYT5, DYT14
MANE Select transcript
ENST00000491895.7NM_000161.3
Locus type
gene with protein product
  • Very high
  • Confident
  • Low
  • Very low

Reference genomeGRCh38

Positions on gene and variant pages follow this choice, in this browser.

Curated reports relevant to this gene

  • BH4 Deficiency & Monoamine Neurotransmitter Disorders

    • Hyperphenylalaninemia due to BH4 DeficiencyAutosomal recessive

      Caused by variants in PTS, QDPR, PCBD1 or GCH1, which raise phenylalanine and reduce dopamine and serotonin, leading to movement problems, seizures and developmental delay.

      • 3 GenCC submitters rate it definitive or strong
      What knowing changes

      Knowing allows treatment with BH4, neurotransmitter precursors (L-dopa, 5-hydroxytryptophan) and folinic acid where needed.

  • Dystonia, Myotonia, Paroxysmal Dyskinesia

    • Dystonia 5

      An autosomal dominant dopa-responsive dystonia in which the cause of the disease is a variation in the GCH1 gene.

      • 4 GenCC submitters rate it definitive or strong
    • Inherited Dystonia

      Umbrella term covering inherited dystonias, including DYT-TOR1A early-onset generalized dystonia, DYT-THAP1, myoclonus-dystonia (SGCE) and KMT2B-related dystonia.

      • 4 GenCC submitters rate it definitive or strong

Inheritance

Autosomal recessive
It takes a changed copy from each parent. With one, you are a carrier and usually unaffected; when both parents are carriers, each child has a one-in-four chance of inheriting two.

How GCH1 is laid out

  • Coding sequence
  • Untranslated region
  • Intron
  • Direction of transcription
  • Known disease-causing sites
  • Stretches short reads find hard
Chromosome 14, with a bracket where GCH1 sits. GCH1 and 13 genes near it on chromosome 14, from 54,372,422 to 55,372,421.Chromosome 1414q22.2p13p12p11.2p11.1q11.1q11.2q12q13.1q13.2q13.3q21.1q21.2q21.3q22.1q22.2q22.3q23.1q23.2q23.3q24.1q24.2q24.3q31.1q31.2q31.3q32.11q32.12q32.13q32.2q32.31q32.32q32.3354.4 Mb54.6 Mb54.8 Mb55 Mb55.2 MbCDKN3: 54,396,849–54,420,221, forward strandCDKN3CNIH1: 54,411,952–54,441,467, reverse strandCNIH1GMFB: 54,474,466–54,489,077, reverse strandGMFBCGRRF1: 54,509,812–54,542,762, forward strandCGRRF1SAMD4A: 54,566,117–54,793,312, forward strandSAMD4AGCH1: 54,842,017–54,902,826, reverse strandGCH1WDHD1: 54,938,949–55,027,450, reverse strandWDHD1SOCS4: 55,027,116–55,049,489, forward strandSOCS4MAPK1IP1L: 55,051,647–55,070,194, forward strandMAPK1IP1LLGALS3: 55,121,352–55,148,027, forward strandLGALS3DLGAP5: 55,132,272–55,191,627, reverse strandDLGAP5FBXO34: 55,271,344–55,384,223, forward strandFBXO34CHMP4BP1: 55,271,378–55,299,503, forward strandCHMP4BP1ATG14: 55,366,391–55,411,831, reverse strandATG14Diagram of GCH1: 6 exons on the reverse strand of chromosome 14Exon 6: 12 known disease-causing sitesExon 5: 10 known disease-causing sitesExon 4: 3 known disease-causing sitesExon 3: 2 known disease-causing sitesExon 2: 3 known disease-causing sitesExon 1: 35 known disease-causing sitesExon 6: 54,842,017–54,844,143, 2,127 basesExon 5: 54,845,768–54,845,852, 85 basesExon 4: 54,847,099–54,847,130, 32 basesExon 3: 54,859,681–54,859,736, 56 basesExon 2: 54,865,327–54,865,436, 110 basesExon 1: 54,902,321–54,902,826, 506 bases6543215′3′

Exons of the gene's MANE Select transcript (release v1.5), from NCBI and EMBL-EBI, on the GRCh38 reference genome.

Chromosome bands from UCSC's GRCh38 ideogram (2022-10-29).

Nearby genes from Ensembl release 116, on GRCh38.

Exons make up 2.9 kb of the gene's 60.8 kb; 753 of those bases code for the protein.

How a genome test reads GCH1

76

positions in GCH1 where ClinVar classes a change as pathogenic or likely pathogenic

None of them falls in a region short reads find hard.

A whole genome covers all 60.8 kb of GCH1, introns included, not only the 2.9 kb of exons.

Where this comes from

  • HGNC: the gene's symbol, name, other symbols and location.
  • MANE Select v1.5, from NCBI and EMBL-EBI: the transcript, its exons and coding sequence.
  • GenCC and ClinGen, released 2026-10-16: which conditions the gene is linked to, and how strongly.
  • The ACMG secondary findings list, SF v3.2.
  • ClinVar and the GIAB stratifications: known disease-causing sites, and the regions short reads find hard.
  • The Human Phenotype Ontology, release 2026-09-01: the traits linked to the gene. Find out more at hpo.jax.org.
  • Data release 2026.10.16-c6eea6bf.

Cite this page

APA

Dante Labs. (n.d.). GCH1 gene: GTP cyclohydrolase 1. Retrieved 17 October 2026, from https://dantelabs.com/genes/gch1

Vancouver

Dante Labs. GCH1 gene: GTP cyclohydrolase 1 [Internet]. [cited 17 October 2026]. Available from: https://dantelabs.com/genes/gch1

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