ASS1 and acute lymphoblastic leukemia: Finally, polymorphisms in other genes that mediate the antileukemic effect of asparaginase, such as the asparaginase synthetase gene (ASNS), the basic region leucine zipper activating transcription factor 5 (ATF5), or the argininosuccinate synthase 1 (ASS1), have been associated to lower event-free survival of ALL patients, albeit the authors reported no associations with adverse effects (Rousseau et al., 2011).