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目的 确定一个染色体隐蔽结构异常的核型 ,探讨染色体表面看来为末端缺失的形成机理。方法 显微切割制备 7号和 7q亚端粒 (7q36→qter)探针 ,通过荧光原位杂交 (FISH)技术分析一例具有反复流产史且常规G带发现有 7q末端缺失的病例。结果 发现该病例为母源的染色体 1p32和 7q32→q35区域之间的隐蔽插入易位 ,7q36→qter区域没有插入到 1号染色体中 ,异常的 7号染色体不是一个末端缺失而是一个中间缺失。结论 本研究为染色体末端区域的插入易位仍然保留其端粒区域提供了实验证据 ,符合三断裂重排的概念。中间缺失可能是解释细胞遗传学上见到的末端缺失的又一个机制。FISH与显微切割技术相结合 ,是检出染色体微小结构异常的一个强有力的工具。
Objective To determine the karyotype of a chromosomal covert structure and investigate the mechanism by which the chromosomal surface appears to be a terminal deletion. Methods 7th and 7th subtelomere (7q36 → qter) probes were prepared by microdissection. One case with a history of recurrent abortion and a 7q deletion in the conventional G band was analyzed by fluorescence in situ hybridization (FISH). As a result, it was found that the case was a covert insertion translocation between the maternal chromosomes 1p32 and 7q32 → q35, the region from 7q36 to qter was not inserted into chromosome 1, and the abnormal chromosome 7 was not an end deletion but an intermediate deletion. Conclusion This study provides experimental evidence that the insertion translocation in the terminal region of the chromosome retains its telomere region and conforms to the concept of triplex rearrangement. Intermediate deletion may be another mechanism for explaining terminal deletions seen on cytogenetically. Combined with microdissection, FISH is a powerful tool for detecting microscopic structural abnormalities in chromosomes.