CXXC5 mRNA expression in AML and control samples.CXXC5 expression was determined in 231 HOVON/SAKK AML cases and 19 normal CD34⁺ by RT-qPCR, calculating the mean cycle threshold difference (∆CT) to ABL, expressed as 2^∆Ct. Jurkat RNA was used as a calibrator between runs. Horizontal lines indicate median expression values. CXXC5 expression in cases with t(8;21) and MLL rearrangements was significantly lower compared with CD34⁺ controls. The other subgroups, including cases with biallelic mutations of CEBPA or mutations involving NPM1, DNMT3A, and ASXL1 genes, showed no significant difference in CXXC5 expression compared with CD34⁺ controls. “Complex karyotype other” indicates cases with complex karyotype without del(5q) or del(7q). **P ≤ .01, ***P ≤ .001 by the Mann-Whitney U test.