FLT3‐ITD mutations were most common in patients characterised by normal karyotype (C1 and C2 P < 0.0001) and rare in core‐binding factor (CBF) leukaemia (C1 P < 0.0001 and C2 P = 0.006) as well as in individuals with complex karyotype (C1 P = 0.004 and C2 P < 0.0001) and inv16 (C1 P < 0.0001 and C2 P = 0.047). The gene discussed is FLT3; the disease is leukemia.