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Hypermethioninemia due to methionine adenosyltransferase deficiency is a very rare metabolic disorder resulting in isolated hepatic hypermethioninemia that is usually benign due to partial inactivation of enzyme activity. Rarely patients have been found to have an odd odor or neurological disorders such as brain demyelination.
Features include sometimes findings: Intellectual disability. 7 total HPO annotations.
Organ System | Phenotype Count | Example Features |
|---|---|---|
Brain and nerves | 3 | Dystonia, Intellectual disability, Overactive reflexes (hyperreflexia) |
MAT1A encodes methionine adenosyltransferase 1A (395 aa). Catalyzes the formation of S-adenosylmethionine from methionine and ATP. Highest expression in Liver (749.3 TPM) and Pancreas (17.2 TPM).
Methionine adenosyltransferase deficiency is caused by mutations in the MAT1A gene on chromosome 10.
The MAT1A protein participates in MAT1A H277Afs*75, MAT1A mutant multimers, and MAT1A mutants:K+:2Mg2+ pathways.
MAT1A is classified as a druggable target (Druggable Genome and Enzyme categories) with score 3.2.
Genetic testing for MAT1A is available. Testing is considered confirmatory for diagnosis.
Estimated prevalence: <1 in 1,000,000 (VERY_RARE).
No clinical trials have been registered for methionine adenosyltransferase deficiency.
4 publications have been identified in PubMed for methionine adenosyltransferase deficiency. Research spans Basic Science / Preclinical (50%), Review / Meta-Analysis (25%), and Case Report / Case Series (25%).
Barbier-Torres L (2025). [PMID: 41462685](https://pubmed.ncbi.nlm.nih.gov/41462685/). *Antioxidants (Basel)*. [Review / Meta-Analysis]
Barbier-Torres L (2025). [PMID: 39922455](https://pubmed.ncbi.nlm.nih.gov/39922455/). *Metabolism*. [Basic Science / Preclinical]
Luque-Urbano MR (2025). [PMID: 40180215](https://pubmed.ncbi.nlm.nih.gov/40180215/). *J Lipid Res*. [Basic Science / Preclinical]
Ma X (2024). [PMID: 39511588](https://pubmed.ncbi.nlm.nih.gov/39511588/). *BMC Pediatr*. [Case Report / Case Series]
Data assembled from 7 of 12 sources · Last updated Sep 19, 2026, 6:54 PM UTC
Online Mendelian Inheritance in Man
European rare disease database
Genetic and Rare Diseases Info Center