MOLECULAR-CYTOGENETIC ANALYSIS OF CHROMOSOMES 5 & 7 IN MYELOID DISORDERS

治疗相关骨髓增生异常综合征（t-MDS）或急性髓系 白血病（t-AML）是细胞毒性治疗的晚期并发症， 恶性和非恶性疾病。 特征递归 染色体5和/或7的异常经常在t- MDS/t-AML。 在我们更新的系列中，我们观察到整个 5号或7号染色体，或缺失[del（5 q）/del（7 q）]的长臂， 246例患者中的175例（71%）接受了检查。 在过去的一段时间里，我们 在5 q31带内描绘了一段5号染色体， 在所有接受检查的患者中，并准备了细胞遗传学图谱， 通常缺失片段的部分基因组重叠群。 我们假设 位于该片段内肿瘤抑制基因可能在该基因中起作用， 在这种疾病的发病机制中的作用。 我们现在建议使用一个 定位克隆和候选基因的方法，以确定一个髓样- 白血病基因5 q31。 第一步将是完成 通常缺失片段的基因组重叠群（3- 4 MB间隔， IL 9和D5 S166）。 将使用几种实验方法来 搜索先前未鉴定的表达序列， 重叠群 以5号染色体异常为特征的白血病细胞 将检查这些候选基因的突变。 如果突变 我们将确定5 q上基因的光谱， 髓系白血病细胞的突变，确定是否突变的 基因是体细胞或生殖系，并确定的后果（S）， 基因/蛋白质功能的突变。 我们计划描绘出 应用细胞遗传学作图技术研究7 q最小缺失片段 检测7 q缺失或易位的白血病细胞。 这些 研究将为进一步的分子研究奠定基础， 7 q上的髓系白血病相关基因。 肿瘤抑制基因还没有得到很好的表征， 恶性血液病 我们希望通过分析反复出现的 缺失，我们可以开始评估隐性突变在 MDS和AML的发病机制，并阐明MDS和AML之间的关系。 既往细胞毒性治疗伴5号染色体基因突变 和7.

Therapy-related myelodysplastic syndrome (t-MDS) or acute myeloid leukemia (t-AML) is a late complication of cytotoxic therapy of both malignant and non-malignant disease. Characteristic recurring abnormalities of chromosomes 5 and/or 7 are frequently noted in t- MDS/t-AML. In our updated series, we observed loss of an entire chromosome 5 or 7, or a deletion of the long arm of [del(5q)/del(7q)] in 175 of 246 (71%) patients examined. In the previous grant period, we delineated a segment of chromosome 5 within band 5q31 that was deleted in all patients examined, and have prepared a cytogenetic map and partial genomic contig of the commonly deleted segment. We hypothesize that a tumor suppressor gene located within this segment may play r role in the pathogenesis of this disease. We now propose to use a positional cloning and candidate gene approach to identify a myeloid- leukemia gene in 5q31. The initial step will be the completion of the genomic contig of the commonly deleted segment (3-4MB interval between IL9 and D5S166). Several experimental approaches will be used to search for previously unidentified expressed sequences within the contig. Leukemia cells characterized by abnormalities of chromosome 5 will be examined for mutations of these candidate genes. If mutations of a gene on 5q are identified, we will determine the spectrum of mutations in myeloid leukemia cells, determine whether mutations of the gene are somatic or germline, and identify the consequence(s) of the mutations on the function of the gene/protein. We plan to delineate the smallest deleted segment of 7q by using cytogenetic mapping techniques to examine leukemia cells with deletions or translocations of 7q. These studies will form the basis for additional molecular studies to isolate a myeloid leukemia-related gene on 7q. Tumor suppressor genes have not been well-characterized in the hematologic malignant diseases. We hope that by analyzing recurring deletions, we can begin to evaluate the role of recessive mutations in the pathogenesis of MDS and AML, and to elucidate the relationship of previous cytotoxic therapy with mutations of genes on chromosomes 5 and 7.