Cumulative incidence of osteonecrosis in patients with ALL according to NWD2 genotype. Cumulative incidence of symptomatic osteonecrosis (grade 2 or higher per the Common Terminology Criteria for Adverse Events, version 4) in children treated on AALL0434 (left) and AALL0232 (right). The T (major) allele at rs2973215 in NWD2 was associated with an increased risk of symptomatic osteonecrosis in both cohorts (hazard ratios of 4.1 and 1.57, respectively); patients with 2 copies of the minor A allele had the lowest risk of this toxicity.