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MAT1A gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

MAT1A gene

The MAT1A gene provides instructions for producing the enzyme methionine adenosyltransferase, which is vital for breaking down methionine and supporting transmethylation processes in the liver.

Normal Function

The MAT1A gene provides instructions for producing the enzyme methionine adenosyltransferase. The enzyme is produced in two forms, MATI and MATII, both of which are found in the liver. MATI is a homotetramer, while MATII is a homodimer.

Both forms help break down the amino acid methionine. The enzyme initiates the conversion of methionine to S-adenosylmethionine (also called AdoMet or SAMe). AdoMet is involved in transmethylation, a process essential for regulating DNA expression, protein and lipid reactions, and the processing of neurotransmitters.

Health Conditions Related to Genetic Changes

Hypermethioninemia

More than 70 variants in the MAT1A gene have been found in individuals with hypermethioninemia, a condition characterized by an excess of methionine in the body. Most of these variants substitute one amino acid for another in the methionine adenosyltransferase enzyme, causing it to process methionine less efficiently. Other variants introduce a premature stop signal, resulting in a shortened, nonfunctional enzyme. These alterations reduce the activity of the enzyme, leading to a buildup of methionine and reduced AdoMet production, which can cause neurological problems in severe cases.

Other Names for This Gene

  • MAT
  • MATA1
  • methionine adenosyltransferase I, alpha
  • METK1_HUMAN
  • S-adenosylmethionine synthetase 1
  • SAMS
  • SAMS, liver-specific
  • SAMS1

Frequently Asked Questions

Patients with MAT1A variants often present with elevated blood methionine levels, which can be detected during newborn screening or routine metabolic panels. Early neurological symptoms may include developmental delays, hypotonia, or seizures, especially if methionine accumulates to high levels.
Confirmation requires a combination of plasma amino acid analysis showing high methionine, a low or normal S‑adenosylmethionine (SAMe) level, and genetic sequencing of the MAT1A gene to identify pathogenic variants. A liver biopsy can also assess enzyme activity if needed.
There is no gene‑specific cure yet. Management focuses on dietary restriction, monitoring methionine and SAMe levels, and treating complications like liver dysfunction or neurological symptoms. In severe cases, liver transplantation has been considered, but it carries significant risks and is not routinely performed.===
Limiting dietary methionine is key; this involves reducing high‑protein foods such as red meat, eggs, dairy, and certain legumes. A dietitian can design a low‑methionine plan that still meets protein needs, often supplemented with essential amino acids that do not contain methionine.
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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