Unidade de Xenética, Instituto de Medicina Legal, and Departamento de Anatomía Patolóxica y Ciencias Forenses, Facultade de Medicina, Universidade de Santiago de Compostela, Santiago de Compostela, Galicia, Spain.
PLoS One. 2009 Nov 18;4(11):e7902. doi: 10.1371/journal.pone.0007902.
Chronic Lymphocytic Leukemia (CLL) leads to progressive accumulation of lymphocytes in the blood, bone marrow, and lymphatic tissues. Previous findings have suggested that the mtDNA could play an important role in CLL.
METHODOLOGY/PRINCIPAL FINDINGS: The mitochondrial DNA (mtDNA) control-region was analyzed in lymphocyte cell DNA extracts and compared with their granulocyte counterpart extract of 146 patients suffering from B-Cell CLL; B-CLL (all recruited from the Basque country). Major efforts were undertaken to rule out methodological artefacts that would render a high false positive rate for mtDNA instabilities and thus lead to erroneous interpretation of sequence instabilities. Only twenty instabilities were finally confirmed, most of them affecting the homopolymeric stretch located in the second hypervariable segment (HVS-II) around position 310, which is well known to constitute an extreme mutational hotspot of length polymorphism, as these mutations are frequently observed in the general human population. A critical revision of the findings in previous studies indicates a lack of proper methodological standards, which eventually led to an overinterpretation of the role of the mtDNA in CLL tumorigenesis.
CONCLUSIONS/SIGNIFICANCE: Our results suggest that mtDNA instability is not the primary causal factor in B-CLL. A secondary role of mtDNA mutations cannot be fully ruled out under the hypothesis that the progressive accumulation of mtDNA instabilities could finally contribute to the tumoral process. Recommendations are given that would help to minimize erroneous interpretation of sequencing results in mtDNA studies in tumorigenesis.
慢性淋巴细胞白血病（CLL）导致淋巴细胞在血液、骨髓和淋巴组织中逐渐积累。先前的研究结果表明，线粒体 DNA（mtDNA）可能在 CLL 中发挥重要作用。
方法/主要发现：分析了 146 名患有 B 细胞 CLL 的患者的淋巴细胞细胞 DNA 提取物和与其粒细胞对应物提取物中的线粒体 DNA（mtDNA）控制区，并将其进行了比较；这些 B-CLL 患者（全部来自巴斯克地区）。为了排除可能导致 mtDNA 不稳定性高假阳性率的方法学假象，并因此导致对序列不稳定性的错误解释，我们做出了重大努力。最终仅确认了二十个不稳定性，其中大多数影响位于第二高变区（HVS-II）中 310 位附近的同质多聚体延伸，这是众所周知的长度多态性的极端突变热点，因为这些突变在一般人群中经常观察到。对先前研究结果的批判性审查表明，缺乏适当的方法学标准，最终导致对 mtDNA 在 CLL 肿瘤发生中的作用的过度解释。
结论/意义：我们的研究结果表明，mtDNA 不稳定性不是 B-CLL 的主要原因。在假设 mtDNA 不稳定性的逐渐积累最终可能有助于肿瘤发生的情况下，不能完全排除 mtDNA 突变的次要作用。我们提出了一些建议，这些建议将有助于最小化 mtDNA 研究中在肿瘤发生中对测序结果的错误解释。
