S-adenosylmethionine treatment in methionine adenosyltransferase deficiency, a case report.

Reported is a female patient with methionine adenosyltransferase I/III (MAT I/III) deficiency, who was found to have pronounced hypermethioninemia on newborn mass spectroscopy screening, and had two compound heterozygous missense mutations in the gene encoding human MAT1A protein. Hypermethioninemia persisted and her mental development was deficient. At 4 years and 8 months, we started with the supplementary treatment of S-adenosylmethionine, the metabolic product of methionine catalyzed by MAT, which was effective in her neurological development.