Glycine N-Methyltransferase Deficiency: A Member of Dysmethylating Liver Disorders?
Glycine N-methyltransferase deficiency is an inherited disorder of methionine metabolism, reported so far in only four patients and characterised by permanent hypermethioninemia. This disorder has been considered as probably benign because moderate hepatomegaly in two patients was the only obvious symptom and mild to moderate elevation of aminotransferases the only laboratory abnormality. Our experience with the current novel patient points out that this disease, due to very high hypermethioninemia, is not harmless and that there may be diagnostic pitfalls in interpretation of biochemical hallmarks of the disease. Since the first description of glycine N-methyltransferase deficiency, other disorders of this metabolic pathway affecting the liver have been reported pointing to dysmethylation as the common pathogenetic mechanism. Therefore, we suggest the whole group to be named dysmethylating liver diseases.
KeywordsGlycine-N-methyltransferase deficiency Hypermethioninemia Inherited liver disease Methylation disorders
The study was supported by the project “European Network and Registry for Homocystinurias and Methylation Defects (E-HOD)” which is co-funded by the European Union in the framework of the Health Program (No.2012_12_02). OV and RB were supported by FP7-REGPOT-2012-2013-1, Grant Agreement Number 316289-InnoMol.
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