论文部分内容阅读
Qinba moutain region is a typical high incidence of mental retardation(MR) in the west of China.In order to reducing MR children in this area , we have studied the causes and the prevention measures for MR since 1995.The results showed that the incidence of MR children in this area was 3.10%, and their main causes included inheritance, iodine deficient, other clinical medicine pathogenesis and social culture badness factors.To analyse the depth genetic causes of MR, the mutation of FMR1 gene had been detected for them by methylation-sensitive restriction endomucleasea(MSRE) and PCR for CpG island methylation and CGG repeats, and PCR-SSCP for the genetic mutations of 17 exons in FMR1 gene.Findings: (1)The CGG repeats number had no significant difference (x2=29.55,P=0.102) between 56 male MR children and their control group(16-40,18-37 respectively).Three FMR1 gene methylated but CGG repeats normal MR children were observed among the male MR children ,and the traits of FXS were observed from part of their family member by physical examination.(2) In the results of detecting mutation of 17 exons in FMR1 gene, a samesense mutation, c.414G>A, was observed in a female serious MR.Compared to the related reports and the results of our study, it suggests that the methylation of CpG island may be a main cause for FXS relative to the expansion of CGG repeats.Additionally,although the detected mutation in our stuty is a nonsense mutation, but it is quite close to the boundary between the fifth exon and the fifth intron, we speculate that it might affect the alternative splicing of the pre-mRNA encoded by FMR1 gene.We will do further exploration in future.