As an uncommon but nonrandom translocation in acute myeloid leukemia (AML) t(5;11)(q31;q23) results in fusion between KMT2A at 11q23 and ARHGAP26 at 5q31. The 5q31 region has another KMT2A partner, AFF4, which was identified in acute lymphoblastic leukemia harboring ins(5;11)(q31;q13q23). We report here a 65-year-old woman with AML M5b. G-banding and spectral karyotyping demonstrated 46,XX,t(5;11)(q31;q23.3). Fluorescence in situ hybridization revealed not only separated 5′ and 3′ KMT2A signals but a faint 5′ KMT2A signal. Reverse transcription polymerase chain reaction (RT–PCR), using a KMT2A sense primer and ARHGAP26 antisense primer, detected no band whereas RT–PCR with a AFF4 antisense primer revealed an amplified band. However, sequence analysis unexpectedly disclosed that KMT2A exon 6 was connected with MLLT10 exons 15 to 18. This may be due to cross-hybridization between MLLT10 exon 18 and AFF4 antisense primer derived from AFF4 exon 10 since both exons had eight identical bases (AAGCAGCT). The MLLT10 gene is located at 10p12.31; a faint 5′ KMT2A signal was probably present at this locus. These findings indicate that in AML the 5′ KMT2A fragment containing exons 1 to 6 may be cryptically inserted into MLLT10 intron 14 when a reciprocal translocation t(5;11)(q31;q23.3) involving KMT2A occurred.

作为急性髓性白血病 (AML) 中一种罕见但非随机的易位，t(5;11)(q31;q23) 导致11q23 处的KMT2A与5q31处的ARHGAP26融合。5q31 区域有另一个KMT2A伙伴AFF4，它在含有 ins(5;11)(q31;q13q23) 的急性淋巴细胞白血病中被发现。我们在此报告一名患有 AML M5b 的 65 岁女性。G 带和光谱核型分析显示 46,XX,t(5;11)(q31;q23.3)。荧光原位杂交不仅揭示了分离的 5' 和 3' KMT2A信号，而且揭示了微弱的 5' KMT2A信号。逆转录聚合酶链反应 (RT–PCR)，使用KMT2A有义引物和ARHGAP26反义引物未检测到条带，而使用AFF4反义引物的 RT-PCR 显示一条扩增条带。然而，序列分析却出人意料地发现，KMT2A外显子 6 与MLLT10外显子 15 至 18相连。这可能是由于MLLT10外显子18 与来自 AFF4 外显子 10 的 AFF4 反义引物之间的交叉杂交，因为两个外显子具有八个相同的碱基 (AAGCAGCT) . MLLT10基因位于10p12.31；该位点可能存在微弱的 5' KMT2A信号。这些发现表明，在 AML 中，包含外显子 1 至 6 的 5' KMT2A片段可能被隐蔽地插入到当发生涉及KMT2A 的相互易位 t(5;11)(q31;q23.3) 时，MLLT10内含子 14 。