近年来,对脆性位点分子生物学的研究已取得突破性进展。脆性X综合征智力低下候选基因FMR-1已被克隆,其5’端外显子是由一段不稳定的微随体序列(CGG)n组成。该(CGG)n重复序列拷贝数的遗传是不稳定的,其扩增长度的变化与脆性位点的表达,CpG岛的甲基化,FMR-1基因的功能,临床表型具有相关性。分子遗传学上把这种独特的遗传形式称为“动态突变”。这一发现,为脆性X综合征及其它与动态突变有关的遗传病的研究提供了重要的线索。 In recent years, the research on the molecular biology of brittle loci has made breakthrough progress. FMR-1, a candidate gene for fragile X syndrome, has been cloned and its 5 ’exon is composed of a fragment of unstable minisatellite sequence (CGG) n. The CGG n repeat copy number was not stable in its inheritance. The variation of its length was related to the expression of brittle loci, CpG island methylation, FMR-1 gene function and clinical phenotype. This unique genetic form is called “dynamic mutation” in molecular genetics. This finding provides important clues for the study of Fragile X syndrome and other genetic diseases related to dynamic mutation.