The t(1;11)(p32;q23) translocation is a rare but recurrent cytogenetic aberration in acute myeloid leukemia (AML) and B-cell acute lymphoblastic leukemia (B-ALL). This translocation was initially shown to form a fusion gene between KMT2A exon 8 at 11q23 and EPS15 exon 2 at 1p32 in AML. Activating mutations of FLT3 are frequently found in AML but are very rare in ALL. Here, we describe a 75-year-old woman who was diagnosed with B-ALL since her bone marrow was made up of 98.2% lymphoblasts. These blasts were positive for CD19, CD22, CD79a, CD13, and CD33 but negative for CD10 and myeloperoxidase. The karyotype by G-banding and spectral karyotyping was 46,XX,t(1;11)(p32;q23). Expression of KMT2A/EPS15 and reciprocal EPS15/KMT2A fusion transcripts were shown: KMT2A exon 8 was in-frame fused to EPS15 exon 12, indicating that this fusion transcript was a novel type. Considering three reported B-ALL cases, EPS15 breakpoints were markedly different between AML (exon 2) and B-ALL (exons 10-12). Furthermore, an uncommon type of FLT3 mutation in the juxtamembrane domain was detected: in-frame 4-bp deletion and 10-bp insertion. Accordingly, our results indicate that the novel type of KMT2A/EPS15 fusion transcript and FLT3 mutation may cooperate in the pathogenesis of adult B-ALL as class II and class I mutations, respectively.

t(1;11)(p32;q23) 易位是急性髓系白血病 (AML) 和 B 细胞急性淋巴细胞白血病 (B-ALL) 中罕见但反复发生的细胞遗传学畸变。这种易位最初显示形成之间的融合基因KMT2A在11q23的外显子8和EPS15在AML外显子2在1p32。FLT3 的激活突变在AML中经常发现，但在 ALL 中非常罕见。在这里，我们描述了一位 75 岁的女性，她被诊断出患有 B-ALL，因为她的骨髓由 98.2% 的淋巴母细胞组成。这些原始细胞对 CD19、CD22、CD79a、CD13 和 CD33 呈阳性，但对 CD10 和髓过氧化物酶呈阴性。G 显带和光谱核型分析的核型为 46,XX,t(1;11)(p32;q23)。KMT2A/EPS15 的表达和倒数显示了 EPS15/KMT2A融合转录本：KMT2A外显子 8 与EPS15外显子 12框内融合，表明该融合转录本是一种新型类型。考虑到三个报告的 B-ALL 病例，AML（外显子 2）和 B-ALL（外显子 10-12）之间的EPS15断点明显不同。此外，在近膜结构域中检测到一种罕见的FLT3突变类型：框内 4-bp 缺失和 10-bp 插入。因此，我们的结果表明，新型KMT2A/EPS15融合转录本和FLT3突变可能分别作为 II 类和 I 类突变在成人 B-ALL 的发病机制中协同作用。