Atypical BCR::ABL1 transcripts are found in approximately 2% of cases of chronic myeloid leukemia. It is important to detect them since affected patients also benefit from tyrosine kinase inhibitor therapy. In the rare e8a2 atypical BCR::ABL1 transcript, two out-of-frame exons are fused, thus, interposed nucleotides are usually found at the fusion site to restore the reading frame. In approximately half of previously reported e8a2 BCR::ABL1 cases, an inserted 55 bp sequence homologous to an inverted sequence from ABL1 intron 1b was detected. The generation of this recurrent transcript variant is not obvious. This work describes the molecular analysis of such an e8a2 BCR::ABL1 translocation from a CML patient. The genomic chromosomal breakpoint is identified, and the formation of this transcript is theoretically explained. The clinical course of the patient is reported, and recommendations are provided for the molecular analysis of future e8a2 BCR::ABL1 cases.

中文翻译：

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插入反向 55 个碱基对 ABL1 内含子 1b 序列的复发性非典型 e8a2 BCR::ABL1 转录本：详细的分子分析。

大约 2% 的慢性粒细胞白血病病例中发现非典型 BCR::ABL1 转录本。检测它们很重要，因为受影响的患者也受益于酪氨酸激酶抑制剂治疗。在罕见的 e8a2 非典型 BCR::ABL1 转录本中，两个框外外显子融合，因此，通常在融合位点发现插入的核苷酸以恢复阅读框。在大约一半先前报道的 e8a2 BCR::ABL1 病例中，检测到与 ABL1 内含子 1b 的反向序列同源的插入 55 bp 序列。这种循环转录变体的产生并不明显。这项工作描述了对 CML 患者的这种 e8a2 BCR::ABL1 易位的分子分析。确定了基因组染色体断点，并从理论上解释了该转录本的形成。报告患者的临床病程，并为未来 e8a2 BCR::ABL1 病例的分子分析提供建议。