Chromosome 21 abnormalities are the most frequent genetic findings in childhood B cell precursor acute lymphoblastic leukemia (BCP-ALL) cases. Majority of patients are effectively diagnosed with fluorescence in situ hybridization (FISH) and karyotyping; however, some cases may require additional tools to be used. Bone marrow samples of 373 childhood BCP-ALL patients were tested for chromosome 21 copy number variations (CNVs) with Multiplex Ligation-dependent Probe Amplification (MLPA) P327 array. Results from MLPA and cytogenetics were compared between groups according to the type of abnormality found on chromosome 21. Out the group of 235 patients, chromosome 21 multiplication was found by FISH assay in 56 cases (23.81%), ETV6-RUNX1 fusion in 34 (14.47%) and iAMP21 in 3 (1.28%) children, remaining 142 (60.43%) patients had no known chromosome 21 aberration. Median peak ratios of all tested probes in MLPA in aforementioned groups were 1.47 (IQR 1.28–1.77) vs. 1.00 (IQR 1.00–1.09) vs. 2.79 (IQR 1.97–2.83) vs. 1.00 (1.00–1.11), respectively. Aforementioned peak ratio of ETV6-RUNX1 fusion group was similar with patients of no known chromosome 21 aberration (p = 0.71). Interestingly, both groups differed from patients with chromosome 21 multiplication (p < 10⁻⁵) and with iAMP21 (p < 10⁻⁵). All cases of iAMP21 were correctly recognized by MLPA. MLPA seems to be good additional tool in the diagnostic process of chromosome 21 CNVs, especially in cases with iAMP21.

中文翻译：

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MLPA 作为诊断儿童 BCP-ALL 21 号染色体畸变的补充工具。


21 号染色体异常是儿童 B 细胞前体急性淋巴细胞白血病 (BCP-ALL) 病例中最常见的遗传发现。大部分患者通过荧光原位杂交（FISH）和核型分析得到有效诊断；然而，某些情况可能需要使用额外的工具。使用多重连接依赖性探针扩增 (MLPA) P327 阵列对 373 名儿童 BCP-ALL 患者的骨髓样本进行了 21 号染色体拷贝数变异 (CNV) 检测。根据21号染色体异常类型对各组间MLPA和细胞遗传学结果进行比较。在235例患者中，FISH检测发现21号染色体增殖56例（23.81%）， ETV6-RUNX1融合34例（34例）。 14.47%）和 iAMP21 存在于 3 名（1.28%）儿童中，其余 142 名（60.43%）名患者没有已知的 21 号染色体畸变。上述组中 MLPA 中所有测试探针的中位峰比分别为 1.47 (IQR 1.28–1.77)、1.00 (IQR 1.00–1.09)、2.79 (IQR 1.97–2.83) 和 1.00 (1.00–1.11)。上述ETV6-RUNX1融合组的峰值比率与无已知21号染色体畸变的患者相似( p =0.71)。有趣的是，两组患者均不同于 21 号染色体增殖 ( p < 10 ^-5 ) 和 iAMP21 ( p < 10 ^-5 ) 的患者。 MLPA 正确识别了所有 iAMP21 病例。 MLPA 似乎是 21 号染色体 CNV 诊断过程中良好的附加工具，尤其是在 iAMP21 病例中。