内皮型一氧化氮合酶基因多态性与神经管畸形的关系

Relationship between gene polymorphism of endothelial nitric synthase and neural tube defects

目的:探讨内皮型一氧化氮合酶基因第4内含子27bp长度的可变数目串联重复序列(VNTR)4a/bVNTR基因多态性和第7外显子单核苷酸多态性G894T与神经管畸形的关系。方法:提取2008年1月～2009年9月间生育神经管畸形儿的30名妇女和同期生育正常儿的60名健康妇女基因组DNA,用PCR-RFLP方法测定G894T和4a/bVNTR的多态性。结果:①eNOS基因G894T位点在本次研究中有3种基因型,即野生型GG、纯合突变型TT和杂合突变型GT。其基因型频率(GG、GT、TT)在病例组中的构成分别为46.67%、40.00%、13.33%,在对照组中的构成分别为73.33%、21.67%、5.00%,两组间的差异有统计学意义(χ2=6.413,P<0.05);其等位基因G的频率在病例组和对照组中的构成分别为66.7%和84.2%,T等位基因的频率分别为33.3%和15.8%,差异有统计学意义(χ2=7.218,P<0.01);②eNOS基因4a/bVNTR位点在本次研究中有两种基因型,即bb型和ab型。其基因型频率(bb、ab)在病例组中的构成分别为63.33%和36.67%,在对照组中的分布频率分别为80.00%和20.00%,在两组中的差异无统计学意义(P>0.05);其等位基因b的频率在病例组和对照组中的构成分别为81.7%和90.0%,a等位基因在病例组和对照组中的分布频率分别为18.3%和10.0%,差异无统计学意义(P>0.05);结论:母亲eNOS基因894位点G→T突变是出生神经管畸形儿的独立遗传学因素,而第4内含子27bpVNTR基因突变不足以构成导致神经管畸形发生的独立遗传学因素。

Objective：To explore the relationship between gene polymorphism of variable number of tandem repeat （VNTR） 4a/bVNTR （27 bp） in the fourth intron of endothelial nitric synthase and single nucleotide polymorphism G894T in seventh extron and neural tube defects.Methods：Genomic DNA were abstracted from 30 women who delivered infants with neural tube defects from January 2008 to September 2009 and 60 healthy women who delivered healthy infants at the same period,PCR-RFLP was used to detect the polymorphisms of G894T and 4a/b VNTR.Results：Three genotypes including wild type GG,homozygous mutant type TT and heterozygous mutant type GT in G894T sites of eNOS gene were found in the study; the proportions of genotypic frequencies of GG,GT and TT in case group were 46.67%,40.00% and 13.33%,respectively; the proportions of genotypic frequencies of GG,GT and TT in control group were 73.33%,21.67% and 5.00%,respectively,there was significant difference between the two groups （χ2=6.413,P〈0.05）; the proportions of allele G in case group and control group were 66.7% and 84.2%,respectively; the proportions of allele T in case group and control group were 33.3% and 15.8%,respectively,there was significant difference （χ2=7.218,P〈0.01）.Two genotypes including bb and ab in 4a/b VNTR sites of eNOS gene were found in the study; the proportions of genotypic frequencies of bb and ab in case group were 63.33% and 36.67%,respectively; the proportions of genotypic frequencies of bb and ab in control group were 80.00% and 20.00%,there was no significant difference between the two groups （P〉0.05）.The proportions of allele b in case group and control group were 81.7% and 90.0%,respectively; the proportions of allele a in case group and control group were 18.3% and 10.0%,respectively,there was no significant difference （P〉0.05）.Conclusion：The maternal G→T mutation in G894T sites of eNOS gene is a independent genetic factor of neural tube defects,VNTR gene mutation in the fourth intron is no enough to compose independent genetic factors of neural tube defects.