中国Rett综合征患儿突变基因的亲源分析

目的 明确中国Rett综合征(Rett syndrome,RTT)患儿致病基因甲基化CpG结合蛋白2(methyl-CpG-binding protein 2,MECP2)的突变亲源.方法 对115例经基因突变分析证实存在MECP2突变的患儿进行第3内含子测序分析,寻找单核苷酸多态性(single nucleotide polymorphism,SNP)位点.对发现SNP患儿行等位基因特异性PCR扩增,通过比较患儿及其父亲SNP碱基序列,判定患儿突变基因所在染色体亲源.结果 115例患儿中76例存在至少一种SNP.在中国RTT患儿中发现3个热点SNP.76例患儿中73例突变位于父源X染色体,3例突变位于母源X染色体.结论 我国RTT患儿MECP2突变以父源突变为主.

Analysis of the parental origin of MECP2 mutations in patients with Rett syndrome

Objective To identify the parental origin of methyl-CpG-binding protein 2 (MECP2)gene mutations in Chinese patients with Rett syndrome. Methods Single nucleotide polymorphisms (SNPs) in intron 3 of the MECP2 gene were analyzed by PCR and sequencing in 115 patients with Rett syndrome.Then sequencing of the SNP region was performed for the fathers of the patients who had at least one SNP,to determine which allele was from the father. Then allele-specific PCR was performed and the products were sequenced to see whether the allele from father or mother harbored the mutation. Results Seventy-six of the 115 patients had at least one SNP. Three hot SNPs were found in these patients. They were: IVS3+22C＞G, IVS3+266C＞T and IVS3+683C＞T. Among the 76 cases, 73 had a paternal origin of MECP2 mutations, and the other 3 had a maternal origin. There were multiple types of MECP2 mutation of the paternal origin, including 4 frame shift, 2 deletion and 67 point (56 C＞T, 6 C＞G, 2 A＞G, 2 G＞T and 1 A＞T) mutations. The mutation types of the 3 ptients with maternal origin included 2 frame shift and 1 point (C＞T) mutation. Conclusion In Chinese RTT patients, the MECP2 mutations are mostly of paternal origin.