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GAMT gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

GAMT gene

The GAMT gene provides instructions for making an enzyme that plays a key role in producing creatine, a compound essential for energy storage and use in the body.

Normal Function

The GAMT gene provides instructions for making the enzyme guanidinoacetate methyltransferase, which is active mainly in the liver. This enzyme participates in the two-step production of the compound creatine from the amino acids glycine, arginine, and methionine. Specifically, guanidinoacetate methyltransferase controls the second step of this process, where creatine is produced from guanidinoacetate. Creatine is needed for the body to store and use energy properly, particularly for muscle contraction and nervous system functioning.

In addition to its role in creatine synthesis, the guanidinoacetate methyltransferase enzyme is thought to help activate a process called fatty acid oxidation. This process provides an energy source for cells during times of stress when their normal fuel, the simple sugar glucose, is scarce.

Health Conditions Related to Genetic Changes

Guanidinoacetate methyltransferase deficiency

At least 49 mutations in the GAMT gene cause guanidinoacetate methyltransferase deficiency, a disorder that involves intellectual disability and seizures. GAMT gene mutations impair the ability of the enzyme to participate in creatine synthesis, resulting in a shortage of creatine. The effects of this deficiency are most severe in organs and tissues that require large amounts of energy, especially the brain.

  • Common Mutation: Most affected individuals of Portuguese ancestry have a particular mutation in which the amino acid tryptophan is replaced by the amino acid serine at position 20 in the enzyme (written as Trp20Ser or W20S).

Other Names for This Gene

  • GAMT_HUMAN
  • PIG2
  • TP53I2

Frequently Asked Questions

Carrier testing confirms status. Options include preimplantation genetic testing (PGT‑M) with IVF to select embryos without two mutant copies, prenatal diagnostic testing (chorionic villus sampling or amniocentesis) with the option of pregnancy continuation decisions, or using donor gametes. Genetic counseling should be pursued to discuss risks and preferences.
Early and continuous creatine monohydrate supplementation (typically 400‑800 mg/kg/day divided into 2–3 doses) can markedly improve seizures, speech, and motor function, especially if started before significant brain injury occurs. However, existing structural brain changes may not fully reverse, so early treatment is critical.
Diagnosis relies on elevated guanidinoacetate and low creatine levels in plasma and urine, plus a reduced GAMT enzyme activity in cultured fibroblasts or liver tissue. Genetic sequencing of the GAMT gene confirms the mutation. Many specialized labs can return metabolic results within 1–2 weeks; genetic sequencing may take 2–4 weeks.
Unlike galactosemia, there are no specific food bans, but a low‑protein diet (especially limiting arginine‑rich foods like red meat, nuts, and soy) can help reduce guanidinoacetate production. Your dietitian will tailor protein intake to age‑appropriate needs while ensuring adequate growth.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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