The ASS gene encodes argininosuccinate synthetase, a liver enzyme involved in nitrogen disposal. Loss-of-function mutations affecting this gene cause autosomal recessive citrullinemia type 1 (classic).
| 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 |
| Clinic | Method | Target mutation analysis |
| Turnaround | 20 days | |
| Specimen type | genomic DNA |