{{Rsnum
|rsid=4411417
|Gene=GCH1
|Chromosome=14
|position=54853845
|Orientation=plus
|GMAF=0.2658
|Assembly=GRCh38
|GenomeBuild=38.1
|dbSNPBuild=141
|geno1=(C;C)
|geno2=(C;T)
|geno3=(T;T)
|Gene_s=GCH1
}}{{ population diversity
| geno1=(C;C)
| geno2=(C;T)
| geno3=(T;T)
| CEU | 4.7 | 32.8 | 62.5
| HCB | 15.6 | 51.1 | 33.3
| JPT | 20.5 | 43.2 | 36.4
| YRI | 1.6 | 43.5 | 54.8
| ASW | 0.0 | 0.0 | 0.0
| CHB | 15.6 | 51.1 | 33.3
| CHD | 0.0 | 0.0 | 0.0
| GIH | 0.0 | 0.0 | 0.0
| LWK | 0.0 | 0.0 | 0.0
| MEX | 0.0 | 0.0 | 0.0
| MKK | 0.0 | 0.0 | 0.0
| TSI | 0.0 | 0.0 | 0.0
| HapMapRevision=28
}}GTP cyclohydrolase and [[tetrahydrobiopterin]] regulate pain sensitivity and persistence. C allele associated with higher tolerance to pain.{{PMID|17057711}}

Polymorphisms in the GTP cyclohydrolase gene ([[GCH1]]) are associated with ratings of capsaicin pain. C allele associated with higher tolerance to pain.{{PMID|19081190|OA=1
}}

{{PMID Auto
|PMID=17343757
|Title=Lack of influence of GTP cyclohydrolase gene (GCH1) variations on pain sensitivity in humans.
|OA=1
}}

{{PMID Auto
|PMID=23322459
|Title=Association of guanosine triphosphate cyclohydrolase 1 gene polymorphisms with fibromyalgia syndrome in a Korean population.
}}

{{on chip | 23andMe v1}}
{{on chip | 23andMe v2}}
{{on chip | 23andMe v3}}
{{on chip | 23andMe v4}}