title: An association study between the transthyretin (TTR) gene and mental retardation.
abstract: It is known that in the pathogenesis of mental retardation (MR), both genetic and environmental factors (particularly iodine deficiency) appear to play a critical role. Transthyretin (TTR) transports between 20% and 30% of serum thyroxine in normal individuals and it is the main T(4)-binding protein in CSF. Variability in the TTR gene may influence risk for iodine-deficiency-based MR. The SNPs we selected from dbSNP were detected and identified using ARMS-PCR and sequencing methods, and we identified five novel sequence variants. Singular-locus association analysis indicated no association between the TTR gene and MR. In haplotype analysis, however, we found a haplotype CGTG+ (rs723744/G+6649C/T+6690C/rs2276382/del9) showed a weak positive association with MR (chi(2) = 6.699, p = 0.035). Finally, we concluded that the weak positive result is more likely to be due to sampling error and the small size of this haplotype resulting from its relative low frequency. Our negative results provide no evidence that variants of TTR gene influence susceptibility to MR in the iodine-deficient areas of China and suggest that there may be a compensatory mechanism(s) in humans and mice, which work(s) to compensate the effect of mutation in the TTR gene on MR.
authors.affiliation: Bio-X Center, Shanghai Jiao Tong University, Shanghai 200030, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
authors.forename: Jian-Jun
authors.initials: JJ
authors.lastname: Gao
authors.forename: Fu-Chang
authors.initials: FC
authors.lastname: Zhang
authors.forename: Qing-He
authors.initials: QH
authors.lastname: Xing
authors.forename: Fang-Li
authors.initials: FL
authors.lastname: Dang
authors.forename: Xiao-Cai
authors.initials: XC
authors.lastname: Gao
authors.forename: Shi-Wei
authors.initials: SW
authors.lastname: Duan
authors.forename: Zi-Jian
authors.initials: ZJ
authors.lastname: Zheng
authors.forename: Xue-Qing
authors.initials: XQ
authors.lastname: Qian
authors.forename: Wei
authors.initials: W
authors.lastname: Qin
authors.forename: Xing-Wang
authors.initials: XW
authors.lastname: Li
authors.forename: Yan-Feng
authors.initials: YF
authors.lastname: Han
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.forename: Guo-Yin
authors.initials: GY
authors.lastname: Feng
authors.forename: D
authors.initials: D
authors.lastname: St Clair
authors.forename: Lin
authors.initials: L
authors.lastname: He
mesh_terms: D002648:Child; D002681:China / Q000453:epidemiology; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006239:Haplotypes; D006801:Humans; D008607:Intellectual Disability / Q000235:genetics*; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D011228:Prealbumin / Q000235:genetics*
chemical_list: D011228:Prealbumin