MEF2D 重排是一种复发性染色体异常，在大约 2.4-5.3% 的急性 B 细胞淋巴细胞白血病 (B-ALL) 患者中检测到。目前，MEF2D重排的B-ALL在WHO分类中并未被列为独立的亚型。因此，MEF2D 重排在 B-ALL 中的临床意义在很大程度上仍未被探索。在本研究中，我们回顾性筛选了 260 名 B-ALL 患者，收集了 2018 年 11 月至 2022 年 12 月期间收集的 RNA 测序数据。其中，10 例患者被鉴定为 MEF2D 重排（4 例为 MEF2D::HNRNPUL1，3 例为 MEF2D::BCL9，1 例为 MEF2D::BCL9）。使用 MEF2D::ARID1B、1 个使用 MEF2D::DAZAP1 和 1 个使用 MEF2D::HNRNPM）。值得注意的是，HNRNPM 和 ARID1B 首次被报道为 MEF2D 融合伙伴。携带 MEF2D::HNRNPM 融合的患者对化疗和嵌合抗原受体 T 细胞治疗具有耐药性，并在同种异体干细胞移植后早期复发。 MEF2D::ARID1B 患者在诊断后出现早期髓外复发。诱导化疗后10例患者全部达到完全缓解。然而，其中 9/10 (90%) 的人经历了复发。 9 名患者中的 3 名因骨髓抗原表达异常而复发。这些患者的中位总生存期仅为 11 个月。这个小队列显示 MEF2D 重排患者早期复发率高且生存期短。© 2024。作者获得 Springer-Verlag GmbH 德国（Springer Nature 旗下公司）的独家许可。

The MEF2D rearrangement is a recurrent chromosomal abnormality detected in approximately 2.4-5.3% of patients with acute B-cell lymphoblastic leukemia (B-ALL). Currently, MEF2D-rearranged B-ALL is not classified as an independent subtype in the WHO classification. Consequently, the clinical significance of MEF2D rearrangement in B-ALL remains largely unexplored. In this study, we retrospectively screened 260 B-ALL patients with RNA sequencing data collected between November 2018 and December 2022. Among these, 10 patients were identified with MEF2D rearrangements (4 with MEF2D::HNRNPUL1, 3 with MEF2D::BCL9, 1 with MEF2D::ARID1B, 1 with MEF2D::DAZAP1 and 1 with MEF2D::HNRNPM). Notably, HNRNPM and ARID1B are reported as MEF2D fusion partners for the first time. The patient with the MEF2D::HNRNPM fusion was resistant to chemotherapy and chimeric antigen receptor T-cell therapy and relapsed early after allogenic stem cell transplantation. The patient with MEF2D::ARID1B experienced early extramedullary relapse after diagnosis. All 10 patients achieved complete remission after induction chemotherapy. However, 9/10 (90%) of whom experienced relapse. Three of the 9 patients relapsed with aberrant expression of myeloid antigens. The median overall survival of these patients was only 11 months. This small cohort showed a high incidence of early relapse and short survival in patients with MEF2D rearrangements.© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.