Search for a rare disease

* (*) mandatory field

Other search option(s)

Suggest an update

(*) Required fields.


Only comments seeking to improve the quality and accuracy of information on the Orphanet website are accepted. For all other comments, please send your remarks via contact us. Only comments written in English can be processed.

Orphanet doesn't provide personalised answers. To get in touch with the Orphanet team, please contact

Information provided in your contribution (including your email address) will be stocked in .CSV files that will be sent as an email to Orphanet's teams. These emails might be conserved in the teams' mailboxes, in our backoffice servers but will not be registered in our databases (for more information see our section General Data Protection Regulation and data privacy (GDPR) and Confidentiality).

Captcha image

Hypermethioninemia due to glycine N-methyltransferase deficiency

Disease definition

Hypermethioninemia due to glycine N-methyltransferase deficiency is a rare, genetic inborn error of metabolism characterized by a relatively benign clinical phenotype, with only mild to moderate hepatomegaly reported, in addition to laboratory studies revealing permanent, greatly increased hypermethioninemia, mild to moderate elevation of aminotransferases and highly elevated plasma S-adenosyl-methionine with normal S-adenosylhomocysteine and total homocysteine.


Classification level: Disorder
  • Synonym(s):
    • Glycine N-methyltransferase deficiency
    • Hypermethioninemia due to GNMT deficiency
  • Prevalence: -
  • Inheritance: -
  • Age of onset: -
  • ICD-10: E72.1
  • ICD-11: 5C50.B
  • OMIM: 606664
  • UMLS: C1847720
  • MeSH: -
  • GARD: 10764
  • MedDRA: -
The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care by a qualified specialist and should not be used as a basis for diagnosis or treatment.