The protein encoded by MAT1A is an important enzyme of sulfur-containing amino acid metabolism. It is mostly that homozygous loss-of-function mutations cause isolated persistent hypermethioninemia and toxic effects on several organs ensue. Although predominantly an recessive disorder, the mutation p.R264H(CGT>CAT) causes a dominant type of inheritance.
| Clinic | Method | Carrier testing |
| Turnaround | 5 days | |
| Specimen type | genomic DNA |
| Clinic | Method | Massive parallel sequencing |
| Turnaround | 25 days | |
| Specimen type | genomic DNA |
| Clinic | Method | Genomic sequencing of the entire coding region |
| Turnaround | 20 days | |
| Specimen type | genomic DNA |