脆性 X综合征是常见的遗传性智力低下性疾病 ,它是正常 FMR1基因 5′端非翻译区 (CGG) n大量扩增的结果。脆性 X综合征的患者 (CGG) n三核苷酸串联重复序列扩增和异常甲基化 ,引起 FMR1基因失活 ,导致 FMR1蛋白 (FMRP)的缺失引起智力低下。FMRP是一种联系核和细胞质之间的 RNA结合蛋白。这种蛋白与蛋白质转运 ,及多聚核糖体和内质网的功能有关。本文综述了 (CGG) n扩增的分子机制研究和 FMRP生物学功能研究的进展。这些研究不仅对探索人类疾病中三核苷酸重复扩增的分子基础有帮助 ,并且对认识人类认知和智力方面也能提供依据 Fragile X syndrome is a common hereditary mental retardation and is the result of extensive amplification of the 5 ’untranslated region (CGG) n of the normal FMR1 gene. Patients with fragile X syndrome (CGG) n trinucleotide tandem repeat amplification and abnormal methylation, causing FMR1 gene inactivation, resulting in the lack of FMR1 protein (FMRP) cause mental retardation. FMRP is an RNA-binding protein that links nuclear and cytoplasmic. This protein is involved in protein transport and the function of the polyribosomes and the endoplasmic reticulum. This review summarizes the molecular mechanisms of (CGG) n amplification and the advances in the biological functions of FMRP. These studies are not only helpful in exploring the molecular basis of trinucleotide repeat amplification in human disease but also provide a basis for understanding human cognition and intelligence