（CAG）n·（CTG）n三核苷酸重复序列扩增及相关疾病机制研究进展

摘要

The dynamic expansion of ( CAG) n· ( CTG) n trinucleotide repeat in certain human genes is tightly associated with the occurrences of neuromuscular degenerative diseases , including multiple types of Spinal-cerebellar Ataxias .The repeating numbers of the relating ( CAG) n· ( CTG) n trinucleotide repeats in normal individuals are lower than a threshold level , while such repeating numbers of the repeats are beyond the threshold in the affiliated genes in patients , leading to the penetrations of different disease symptoms that mainly involve the neuro-and muscular systems .This review summarizes the disease condi-tion and the pathological characteristics of the ( CAG) n· ( CTG) n repeat expansion-associated human disea-ses in China while discussing the possible molecular mechanisms underlying the ( CAG) n· ( CTG) n repeat expansion in vivo .%出现在基因内三核苷酸重复序列（ CAG） n·（ CTG） n的“动态”扩增与包括多型脊髓小脑共济失调在内的神经-肌肉系统退行性病变的发生密切有关。正常个体中，相关（CAG）n·（CTG）n三核苷酸重复序列的重复单元数目被限制在一定的阈值之下，而在患者的受累基因内，（ CAG） n·（ CTG） n的重复数则超出该阈值，并导致患者出现与神经和肌肉系统有关的疾病症候。本文总结归纳了与（ CAG） n·（ CTG） n重复扩增相关的疾病在国内的发病情况和相关疾病的病理特征，并分析讨论了（ CAG） n·（ CTG） n序列在患者体内出现扩增的可能分子机制。