GTP cyclohydrolase I deficiency with hyperphenylalaninemia: genes and variants
GTP cyclohydrolase I deficiency with hyperphenylalaninemia is linked to 1 analyzed protein (GCH1). 1 DNA variants are known to cause it; 7 more are uncertain, and 0 of those already look disease-causing on computable evidence.
Last updated 2026-09-30. Research information, not medical advice.
Genes linked to GTP cyclohydrolase I deficiency with hyperphenylalaninemia
GCH1: GTP cyclohydrolase 1
It catalyzes the rate-limiting step in tetrahydrobiopterin synthesis, supplying an essential cofactor for dopamine, serotonin, norepinephrine, and nitric-oxide production. Dominant loss-of-function variants classically cause dopa-responsive dystonia, while biallelic deficiency can produce severe neurotransmitter disease.
1 disease-causing and 7 uncertain variants in GCH1 are linked to GTP cyclohydrolase I deficiency with hyperphenylalaninemia.
Known disease-causing variants in GTP cyclohydrolase I deficiency with hyperphenylalaninemia
| Variant | Position | Protein part | Clinical label |
|---|---|---|---|
| GCH1 M211I | 211 | Disease-causing |
Same protein, different disease
- GTP cyclohydrolase I deficiency is also caused by GCH1 variants; they fall mostly in different places as the GTP cyclohydrolase I deficiency with hyperphenylalaninemia variants (19 disease-causing).
Diseases related to GTP cyclohydrolase I deficiency with hyperphenylalaninemia
- Autosomal recessive DOPA responsive dystonia, also linked to GCH1
- GTP cyclohydrolase I deficiency, also linked to GCH1
Frequently asked questions
Which genes are linked to GTP cyclohydrolase I deficiency with hyperphenylalaninemia?
In CATVariant, GTP cyclohydrolase I deficiency with hyperphenylalaninemia is linked to 1 analyzed protein: GCH1 (GTP cyclohydrolase 1).
How many genetic variants are linked to GTP cyclohydrolase I deficiency with hyperphenylalaninemia?
11 variants: 1 are classified as disease-causing (pathogenic or likely pathogenic) in ClinVar and 7 are of uncertain significance or have conflicting reports.
Which uncertain variants in GTP cyclohydrolase I deficiency with hyperphenylalaninemia look disease-causing?
None of the uncertain variants currently reaches the likely-pathogenic range on computable evidence alone.
About this data
Variant–disease links come from ClinVar, Open Targets and UniProt, pooled from the latest public CATVariant analysis of each human protein. Evidence scores use the ACMG/AMP Bayesian points scale with computable criteria only (position among known disease variants, rarity in gnomAD, calibrated predictors, deep mutational scanning); there is no family or patient data, so they prioritise variants for expert review and never classify them.
Download every variant as CSV · Browse all diseases · Methods · About the Center