The use of high-throughput analytical techniques has enabled the description of acute lymphoblastic leukaemia (ALL) subtypes. The TCF3-HLF translocation is a very rare rearrangement in ALL that is associated with an extremely poor prognosis. The TCF3-HLF fusion gene in the described case resulted in the fusion of the homeobox-related gene of TCF3 to the leucine zipper domain of HLF. The TCF3-HLF fusion gene product acts as a transcriptional factor leading to the dedifferentiation of mature B lymphocytes into an immature state (lymphoid stem cells). This process initiates the formation of pre-leukaemic cells. Due to the rarity of this chromosomal aberration, only a few cases have been described in the literature. The advantage of this work is the presentation of an interesting case of clonal evolution of cancer cells and the cumulative implications (diagnostic and prognostic) of the patient’s genetic alterations. This work presents a patient with diagnosed with TCF3-HLF-positive ALL. Moreover, the additional genetic alterations, which play a key role in the pathogenesis of ALL, were detected in this patient: deletion of a fragment from the long arm of chromosome 13 (13q12.2-q21.1) containing the RB1 gene, intragenic deletions within the PAX5 gene and NOTCH1 intragenic duplication. A patient with coexistence of chromosomal alterations and the TCF3-HLF fusion has not yet been described. Identifying all these chromosomal aberrations at the time of diagnosis could be sufficient to determine the cumulative effects of the described deletions on the activity of other oncogenes or tumour suppressors, as well as on the clinical course of the disease. On the other hand, complex changes in the patient’s karyotype and clonal evolution of cancer cells call into question the effectiveness of experimental therapy.

中文翻译：

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TCF3-HLF阳性BCP-ALL患者的综合染色体畸变。

高通量分析技术的使用已使急性淋巴细胞白血病（ALL）亚型的描述成为可能。TCF3-HLF易位是ALL中非常罕见的重排，与预后极差有关。在所述情况下，TCF3-HLF融合基因导致TCF3的同源盒相关基因与HLF的亮氨酸拉链结构域融合。TCF3-HLF融合基因产物充当转录因子，导致成熟的B淋巴细胞去分化为未成熟状态（淋巴干细胞）。这个过程启动了白血病前细胞的形成。由于这种染色体畸变的罕见性，文献中仅描述了少数情况。这项工作的优点是可以介绍一个有趣的癌细胞克隆进化案例，以及患者遗传改变的累积影响（诊断和预后）。这项工作介绍了一名诊断为TCF3-HLF阳性ALL的患者。此外，在该患者中发现了在ALL发病中起关键作用的其他遗传改变：从RB13基因的13号染色体长臂（13q12.2-q21.1）的片段中删除了PAX5基因内缺失和NOTCH1基因内复制。尚未描述具有染色体改变和TCF3-HLF融合并存的患者。在诊断时识别所有这些染色体畸变可能足以确定所述缺失对其他癌基因或肿瘤抑制物的活性以及对疾病的临床进程的累积影响。另一方面，患者核型的复杂变化和癌细胞的克隆进化令人质疑实验疗法的有效性。