一直以来，科学家们都确信每个细胞内的DNA都是相同的。而一项最近的研究成果却对此提出了质疑，蒙特利尔大学的研究人员最近发现，并不是所有的细胞中的DNA都是相同的。这一发现对过去15年对人类疾病的研究有重大意义。由于对于癌症以外的其他疾病，研究人员很难从患者身上采集病变标本，因此，研究人员一直都致力于研究血液。然而，如果事实证明，血液和组织细胞的基因不匹配，那么这些研究或许从一开始就是有缺陷的。这一发现将发表在7月的《人类突变》杂质上。
本次发现源于施韦策博士，布鲁斯博士和洛林博士及其同事对主动脉瘤遗传原因的研究。当他们重点研究控制细胞死忙的BAK基因时，他们有了惊人的发现。主动脉瘤是一种非常罕见的脑血管疾病，当他们对同一个患者的血细胞和组织细胞的BAK基因进行比较发现，这两种细胞内的BAK基因有着明显区别。随后，他们又对健康人两种细胞内的进行了比较，同样发现了这种差异。
研究人员解释道：“对于癌症以外的其他疾病，通常我们只能对血液进行研究，传统上，当我们试图寻找一些疾病的遗传因素时，血液将告诉我们组织的变化，而现在看来，却好像不是这样的。除去治疗的影响不计，单纯从遗传学角度看，不是每个细胞都相同这是非常重要的。早些年，人们就对基因组关联大肆宣传，研究人员从成千上万的人中提取血液样本进行研究，然而，他们期盼的巨大突破却一直没有，或许，我们的发现可以解释其失败的某些原因。”
主动脉瘤主要影响一些吸烟，有高血压和高胆固醇的老年人，它往往没有症状，但在99%的情况下。其可导致主动脉破裂而死亡。研究人员认为，这一发现或许将为我们治疗主动脉瘤带来新的方法，并缩短其治疗周期，如果真的实现的话，这将是个十分重大的突破。（生物谷Bioon.com）
生物谷推荐原始出处：
Human Mutation Volume 30 Issue 7, Pages 1043 - 1047
BAK1 gene variation and abdominal aortic aneurysms
Bruce Gottlieb 1 2 *, Lorraine E. Chalifour 1 3 4 5, Benjamin Mitmaker 6, Nathan Sheiner 6, Daniel Obrand 6, Cherrie Abraham 6, Melissa Meilleur 1, Tomoko Sugahara 1, Ghassan Bkaily 7, Morris Schweitzer 1 4
1Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montréal, Québec, Canada
2Department of Human Genetics, Department of Medicine, McGill University, Montréal, Canada
3Division of Experimental Medicine, McGill University, Montréal, Canada
4Departments of Endocrinology, McGill University, Montréal, Canada
5Bank of Montreal Research Center for the Study of Heart Disease in Woman, McGill University, Montréal, Canada
6Department of Surgery, Sir Mortimer B. Davis-Jewish General Hospital, McGill University, Montréal, Canada
7Department of Anatomy and Cell Biology, University of Sherbrooke, Quebec, Canada
We sought to examine the role of genetics in the multifactorial disease, abdominal aortic aneurysm (AAA), by studying sequence variation in the BAK1 gene (BAK1) that codes for an apoptotic-promoting protein, as chronic apoptosis activation has been linked to AAA development and progression. BAK1 abdominal aorta cDNA from AAA patients and nondiseased individuals were compared with each other, as well as to the BAK1 genomic sequence obtained from matching blood samples. We found specific BAK1 single nucleotide polymorphism (SNP) containing alleles in both aneurysmic (31 cases) and healthy aortic tissue (5 cases) without seeing them in the matching blood samples. These same BAK1 SNPs have been reported, although rarely (average frequency <0.06%), in reference BAK1 DNA sequences. Based on this and other similar observations, we propose a novel hypothesis postulating that multiple variants of genes may preexist in minority forms within specific nondiseased tissues and be selected for, when intra- and/or extracellular conditions change. Therefore, the fact that different BAK1 variants can exist in both diseased and nondiseased AA tissues compared to matching blood samples, together with the rare occurrence of these same SNPs in reference sequences, suggests that selection may be a significant factor in AAA ontogeny. Hum Mutat 30:1-5, 2009. ? 2009 Wiley-Liss, Inc.
