父母MTHFR基因型对后代发生神经管畸形的影响

本研究旨在探讨父母双方MTHFR基因型与其后代发生神经管畸形风险性的关 系。采用成组匹配的病例对照研究方案,用纸片法采集病例和对照外周血标本,用PCR-RFLP方法确定基因型(C677T)。结果显示,分别比较两组父亲或母亲基因型频率时,差别不显著;将父母基因型联合起来分析则发现,病例组父母等位突变基因频率(T)高于对照组父母,提示后代是纯合突变( TT)概率越大,发生NTD的风险性也越大。结论是,父母双方的基因型对后代发生NTD的风险性有同等重要的作用,父母双方传递给胎儿的一对突变等位基因(T/T)是NTD发生的风险因素之一。 Abstract:The effect of parental MTHFR genotypes on fetal phenotype of NTD is studied.It was designed as group matched case-control study.Venous blood cases and controls were collected by dry blood spots.Genotype(C677T)of each sample was decided by PCR-RFLP method.When the genotypes of father and mother are compared separately,no significant difference is discovered between cases and controls.On the other hand,when the mutant allele frequency(T)is computed for father and mother together,it is significantly higher in cases than in controls.Higher probabilities of the offspring being homozygotes(TT),higher the risk for NTD occurrence has been observed.It is concluded that genotypes of MTHFR for both father and mother have the same impact on NTD occurrence of their offspring.It is the pair of mutant allele(T/T)which transmitted to the baby from its parents that increases the risk.     

类固醇5-α还原酶样基因Srd5α2l2的克隆及表达分析

采用表达序列标签（EST）介导的基因克隆和表达谱分析,从小鼠心脏克隆了一个cDNA为2 348 bp,主要在心脏表达的新基因Srd5α2l2（GenBank Acc No.AF548365）.该基因由12个外显子组成,3′非翻译区富含ATTTA序列,最大开放阅读框编码一个由361个氨基酸组成的假定蛋白,该蛋白质C端含有类固醇5-α还原酶的保守结构域（3-oxo-5-alpha-steroid 4-dehydrogenase,STEROID_DH）.生物信息学分析表明,人cDNA 克隆DKFZp313D0829（AL833108）是Srd5α2l2的人同源基因.经同源性检索,支持Srd5α2l2的全部41条EST中25条来自小鼠心脏组织.RT-PCR检测初步证实,该基因主要在心脏中表达,而在其他组织中不表达或弱表达.综合考虑Srd5α2l2的序列特征和表达谱,Srd5α2l2可能在心脏组织中发挥重要作用.     

中国汉蒙两族人群MTHFR基因热敏感性多态性分布的比较

为比较中国蒙汉两族人群MTHFR基因第677位核苷酸多态性的分布情况,获得该位点多态性的群体遗传学数据,本研究应用PCR扩增技术, 其扩增产物用限制性核酸内切酶Hinf I消化后进行非变性聚丙烯酰胺凝胶电泳,分析蒙汉族人群中MTHFR基因第677位核苷酸基因型（野生型、杂合型和突变纯合型）的分布频率。结果表明,蒙族人群基因型构成以野生型为主,占45.6％,突变杂合型占39.2％,突变纯合型仅占15.2％,汉族人群基因型构成以突变杂合型为主,占55.7％,野生型仅占17.9％,突变纯合型占26.4％,明显高于蒙族人群。经χ2检验,两组基因型构成比具有显著性差异（P<0.001）;蒙族人群MTHFR 677T等位基因频率为34.8％,经u检验显著低于汉族人群（54.2％）的频率。据此认为,中国蒙族人群MTHFR热敏感性基因突变频率显著低于汉族人群,提示该基因多态性分布在中国不同民族人群中存在差异。 Abstract：The purpose of this study is to compare the genetic polymorphism distribution of the 677th nucleotide of MTHFR between the Mongolian population and the Hans of China,and to obtain the population genetic data of this polymorphism.Using PCR－RFLP method,the authors analyzed the genotypes of the 677th nucleotide of MTHFR in Mongolians and Hans.Results show that in Mongolian population,the proportion of wild type is 45.6％,proportion of heterozygotes is 39.2％ and that of homozygotes is 15.2％; While in Hans,proportions are wild type 17.9％,heterozygotes 55.7％ and homozygotes 26.4％.The ratios of genotypes are significantly different between Mongolian and Han populations(χ2－test,P<0.001).The 677th allele frequency in Mongolians is 34.8％,lower than that in Hans(54.2％,u－test,P<0.001).This suggests that the mutant MTHFR gene frequency is significantly higher in the Han population than in the Mongolian population in China.