As in the work by Tonks et al. [28], aberrant CD200 expression was detected in the vast majority (93%) of AML cases with favorable cytogenetic, but we found high rate of CD200 positivity also in patients with unfavorable katyotype (P = 0.0003), NPM1 wild type (P = 0.001), Flt3-ITD negative (P = 0.004), and with unfavorable cytogenetic/molecular status, as recently defined by Döhner [9] (P = 0.02). The gene discussed is NPM1; the disease is acute myeloid leukemia.