Accumulation of Genetic Alterations and Chromosome Abnormalities in the Onset and Subsequent Progression of Myelodysplastic Syndromes

本项目对骨髓增生异常综合征（MDS）发病和进展过程中遗传事件的积累进行了研究，主要发现了以下三点：(1)在176例髓系白血病患者中，包括85例MDS患者在内的5例（2.9%）患者中发现了AML1 Runt结构域的精细突变事件。在这5例患者中，有4例患者完全出现了由多个碱基对缺失或插入引起的移框突变，分别为V93del、1150ins、I168ins和A120ins。在他们的疾病过程中的纵向分析显示，在第一个样本中检测到所有突变，这意味着MDS中的AML1突变可能是在发病和随后的疾病进展期间积累的最早的遗传改变之一。(2)为了研究DNA修复基因的突变事件，我们尝试优化了68个基因的1108个外显子的测序程序，目前已经完成了924个外显子的优化。在这68个基因中，我们使用48例MDS患者、48例恶性淋巴瘤患者和48例AML患者的骨髓细胞DNA样本，分析了6个DNA错配修复基因的97个外显子。在成功分析的79个外显子（编码区14753个碱基对）中，鉴定出31个突变事件，其中hMLH1 7个，hMSH2 1个，hMSH6 3个，hPMS1无突变，hPMS2 9个。(3)我们验证了国际预后评分系统（IPSS）在新发MDS患者中的有效性。我们还揭示了这些患者p53结构的预后意义，多因素分析发现其结构是最重要的预后因素，其次是IPSS风险分层。此外，在相同的IPSS类别中，p53突变患者的生存时间明显短于野生型患者

This project on the accumulation of genetic events during the onset and the progression of myelodysplastic syndrome (MDS) revealed three major points as follws:(1) Refined mutational events in the Runt domain of the AML1 gone were identified in 5 patients (2.9%) of 176 patients with myeloid leukemia including 85 with MDS. Among these 5 patients, 4 exclusively showed a frame-shift mutation caused by several base-pairs deletion or insertion, resulting in V93del, 1150ins, I168ins and A120ins, respectively. Longitudinal analyses during their disease course revealed all mutations were detected in the first sample, which means AML1 mutations in MDS may be one of the earliest genetic alterations accumulated during the onset and subsequent disease progression.(2) In order to investigate mutational events in DNA repair genes, we tried to optimize sequencing procedures for 1108 exons of 68 genes, and the optimization for 924 exons has already been finished. Among these 68 genes, we analyzed 97 exons of 6 DNA mismatch repair genes using DNA samples from marrow cells from 48 patients with MDS, 48 with malignant lymphoma, and 48 with AML. Among 79 exons (14753 base-pairs in coding regions) successfully analyzed, 31 mutational events were identified, which involved 7 in hMLH1, 1 in hMSH2, 3 in hMSH6, none in hPMS1, and 9 in hPMS2.(3) We validated the usefulness of the International Prognostic Scoring System (IPSS) in our series of de novo MDS patients. We also revealed the prognostic significance of p53 configurations of those patients, and multivariate analysis uncovered its configuration was the most important prognostic factor, followed by the IPSS risk-stratification. Moreover, within the same IPSS category, patients with a p53 mutation showed significantly shorter survival time than those with wild-type configuration