Methionine Adenosyltransferase I/III Deficiency (MAT1A)
Methionine adenosyltransferase I/III deficiency is an autosomal recessive disorder caused by pathogenic variants in the gene MAT1A. Many patients with this disorder have no clinical abnormalities and are considered “clinically benign”, although some have been reported to have neurologic abnormalities such as developmental delay, intellectual disability, or brain demyelination caused by hypermethioninemia. Affected individuals may also have a distinctive odor, similar to boiled cabbage, in their urine, sweat, and breath. Life expectancy for this disorder is normal, and no clear genotype-phenotype correlation has been reported. Some individuals with heterozygous variants may exhibit clinical symptoms of the disorder.
For information about carrier frequency and residual risk, please see the residual risk table.