Together, a cohort of 209 ALL patients were investigated, which is not restricted to a particular genetic subgroup (listed in Supplementary Table 3), and the prevalence of JAK1 mutations were found at a frequency of approximately 2.4% in ALL (5/209), especially more common in T-ALL (2/19) than in B-ALL (3/190) (10.5% versus 1.6%, P < 0.05) (Table 2). Here, JAK1 is linked to acute lymphoblastic leukemia.