The combined incidence of 12q CN-LOH and/or deletion of the region including SH2B3 was 9/49 (18%) in iAMP21-ALL, in marked contrast to non-iAMP21-ALL, where among 253 patients only two were seen (0.8%) and both cases carried OSA21. The gene discussed is SH2B3; the disease is acute lymphoblastic leukemia.