智力低下儿童X染色体脆性位点及FMR1基因突变的研究

目的探讨智力低下（Mental Retardation，MR）儿童染色体遗传学原因。方法选择智力低下患儿及其父母作为研究对象，采用细胞遗传学方法检测X染色体脆性位点，以及采用多重连接探针扩增（Multiplex ligation—dependent Probe Amplificaton，MLPA）技术分析FMRl（Fragile X mental retardation gene1）基因的缺失与重复。结果266例患儿共查出X脆性综合征18例，与父母同一脆性位点的7例，其中6例为FMRl基因突变。结论MR患儿可与表型正常的父母有同-X染色体脆性位点，但FMRl基因突变是X脆性综合征（Fragile X syndrome，Fra X）临床表型的真正原因。

Study on X chromosome fragile site and FMRl gene mutation in children with metal retardation

Objective： To explore the genetic reasons of metally retarded children. Methods： Xq27 fragile site and FMR1 gene mutation were examined by cytogenetics and MLPA respectively. Results： We detected 18 children with Fra （X）, and found out 7 children had the same fragile site with their parents, in those 6 had FMR1 gene mutation. Conclusions： MR children have the same fragile site in X chromosome with their parents, but FMR1 gene mutation is the primary cause for fragile X syndrome.