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Updated: Jul 29, 2026
06:07
Continuous Fluorescence-Based Endonuclease-Coupled DNA Methylation Assay to Screen for DNA Methyltransferase Inhibitors
Published on: August 5, 2022
Glycine N-methyltransferase deficiency: a novel inborn error causing persistent isolated hypermethioninaemia
S H Mudd1, R Cerone, M C Schiaffino
1Laboratory of Molecular Biology, National Institute of Mental Health, Bethesda, Maryland 20892-4034, USA. shm@codon.nih.gov
Journal of Inherited Metabolic Disease
|October 13, 2001
Summary
Two siblings with persistent hypermethioninemia were found to have glycine N-methyltransferase (GNMT) deficiency. This novel finding may explain their mild liver issues and suggests potential dietary interventions.
Area of Science:
- Biochemistry
- Genetics
- Metabolic Disorders
Background:
- Persistent isolated hypermethioninemia is a rare metabolic condition.
- Previous research has excluded common causes like cystathionine beta-synthase deficiency and liver disease.
Observation:
- Two Italian siblings presented with persistently elevated plasma methionine levels beyond infancy.
- Metabolic studies ruled out deficiencies in methionine adenosyltransferase, methylenetetrahydrofolate reductase, and guanidinoacetate methyltransferase.
Findings:
- The siblings exhibited normal plasma sarcosine levels, indicating a deficiency in glycine N-methyltransferase (GNMT) activity.
- This GNMT deficiency is a novel cause of persistent hypermethioninemia.
Implications:
- GNMT deficiency may be linked to mild hepatomegaly and elevated serum transaminases.
- Further research is needed to explore dietary methionine restriction as a potential therapeutic strategy.
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