A Study On The Correlation Between FMR1 And Mental Retardation Of Children In QinBa Arear

Mental retardation,with prevalence incidence of about 1%～3%,is a serious children's mental and neural disease.The etiology causing this disease is very complicated.Many research results showed that the genetic variations in FMR1 gene are underlying causes in mental retardation.The CGG repeats and methylation of CpG island in FMR1 gene were detected to study the cause of MR children from both Zhashui and Ankang locations of Qinba mountain south of China,which underlies the pedigree investigation and clinical check done by our research group.The unusual expand of(CGG) n was not found in patients except three ones with striking methylation of CpG island.This result indicated that the unusual methylation of CpG island in FMR1 gene may be one of the pathogenic factors leading to MR of the three children.Previous researches suggested that multiple types of mutants in FMR1 gene were relevant to MR.Therefore,we chose the genetic marker sites in FMR1 gene to explore the relationship between other types of mutants of this gene and MR.affecting children from both Zhashui and Ankang locations of Qinba mountain south of China while the Case-Control analysis method is adopted.In this study we chose 128 MR children,126 border children and 342 normal controls as our research objects.The genotype methods towards three SNPs (rs4949,rs25714 and rs25704) genetic markers were used by Polymerases Chain Reaction and Single Strand Conformation Polymorphism(PCR-SSCP),followed by correlation analysis between the variations of rs4949,rs25714 and rs25704 and MR using association analysis method.The separate loci analysis showed that there is no significant correlation (p=0.50 and p=0.46,p=0.55 and p=0.37,p=0.91 and p=0.91) between the distribution of genotype and allelic frequency and the individual SNPs(rs4949,rs25714 and rs25704) in female children among the MR group and normal group respectively,which is the same in male children among the MR group(p=0.19,p=0.12 and p=0.14,respectively).These results indicated that there is no significant correlation between the genetic polymorphism of three SNPs(rs4949,rs25714 and rs25704) in FMR1 gene and MR children from both Zhashui and Ankang locations of Qinba mountain south of China,which suggested that,except methylation of CpG island in the upstream promoter region,other types of mutants in FMR1 gene may be not associated with children with MR in this area.However, the primary conclusion is still needed to further investigation and exploration.