The ASNS gene codes for the glutamine-dependent asparagine synthetase enzyme that catalyzes the transfer of ammonia from glutamine to aspartic acid via a β-aspartyl-AMP intermediate to form asparagine. This gene complements a mutation in the temperature-sensitive hamster mutant ts11, which blocks progression through the G1 phase of the cell cycle at nonpermissive temperature.
Mutations in this gene cause Asparagine Synthetase Deficiency, an extremely rare neurodevelopmental disorder, characterized by congenital microcephaly, severely delayed psychomotor development, progressive encephalopathy, and cortical atrophy, associated with seizure or hyperekplexia. Asparagine Synthetase is used clinically as one of the components in multi-agent treatment protocol of childhood Acute Lymphoblastic Leukemia.