同型半胱氨酸及亚甲基四氢叶酸还原酶基因多态性与缺血性卒中的关系研究

Analysis of Relationship of Plasma Homocysteine Level and Polymorphism of Methylenetetrahydrofolate Reductase with Ischemic Stroke

目的探讨同型半胱氨酸(homocysteine,Hcy)水平及亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase,MTHFR)基因多态性与缺血性卒中(ischemic stroke,IS)的关系,并分析Hcy与叶酸、Vit B_(12)之间的相关性。方法运用酶循环法和聚合酶链式反应(polymerase chain reaction,PCR)-芯片杂交法分别检测217例IS患者和223例对照者血浆Hcy与MTHFR C667T基因型,并对照分析两组的基因型频率和等位基因频率分布差异及血浆Hcy水平;运用免疫分析法检测两组中既往未服用过含叶酸和Vit B_(12)药物的88例IS患者和125例对照者血清叶酸、Vit B_(12)水平,并与Hcy水平进行相关性分析。结果 IS组Hcy浓度高于对照组,差异有显著性([23.95±12.13)μmol/L vs(17.31±7.20)μmol/L,t=29.61,P<0.001],IS组与对照组MTHFR基因型频率CC、CT、TT型分别为14.3%、44.7%、41.0%和18.4%、48.9%、32.7%,等位基因C与T的频率分别为36.6%、63.4%和42.8%、57.2%,无显著性差异(基因型频率:χ~2=3.59,P=0.166;基因频率:χ~2=3.52,P=0.061)。MTHFR基因TT型(162例)、CT型(206例)和CC型(72例)的血浆Hcy水平分别为(25.19±12.53)μmol/L、(18.21±8.08)μmol/L和(16.65±6.90)μmol/L,其中TT型显著高于CT型和CC型,CT型显著高于CC型(P均<0.001)。IS组和对照组血浆Hcy水平与Vit B_(12)呈负相关(IS组和对照组分别为r=-0.431,P<0.001和r=-0.507,P<0.001),与叶酸亦呈负相关(IS组和对照组分别为r=-0.489,P<0.001和r=-0.446,P<0.001)。结论 IS患者血浆Hcy水平较正常人偏高;MTHFR C667T基因突变、叶酸和Vit B_(12)水平降低是血浆Hcy水平升高的影响因素;MTHFR C667T基因突变可能与缺血性卒中无关。

Objective To investigate the relationship of the plasma homocysteine （Hcy） level and the polymorphism of methylenetetrahydrofolate reductase C667T （MTHFR C667T） gene with ischemic stroke （IS） in China, and analyze the correlation between Hcy and folate, VitB12. Methods The levels of plasma Hcy in 217 patients with IS and 223 matched controls were detected by enzymatic recycling method, and the MTHFR C667T genotype of the two groups by the method of polymerase chain reaction （PCR）-gene chip, then the level of plasma Hcy, the genotype frequency and the alleles distribution in two groups were compared. The levels of serum folate and VitB12 were detected by immunoassay method in 88 patients with IS and 125 controls who had not taken drugs containing folic acid or VitB12, and the correlation between folate, VitB12 and Hcy were analyzed. Results The plasma Hcy concentration in the IS group was higher than that in control group （[23.95±12.13] μmol/L vs [17.31±7.20] μmol/L, t=29.61, P〈0.001）; however, the frequency of homozygous and heterozygous MTHFR mutation between the two groups had no significant difference （χ^2=3.59, P=0.166）, the frequency of allele C and T in the IS group were 36.6% and 63.4%, respectively, 42.8% and 57.2% in control group, there was also no significant difference in the two groups （χ^2=3.52, P=0.061）. There was a significant difference in the corresponding plasma Hcy level of CC, CT, TT genotype, the plasma Hcy level of TT genotype （[25.19±12.53]μmol/L, n=162） was significantly higher than that of CT （[18.21±8.08] μmol/L,n=206） and CC （[16.65±6.90]μmol/L, n=72） genotype, and that of CT genotype was significantly higher than CC genotype （all P〈0.001）. The Hcy level was negatively correlated with VitB12 in the two groups （the IS： r=-0.431, the control： r=-0.507, both P〈0.001） and also negatively correlated with folate（the IS： r= -0.489, the control： r=-0.446, both P〈0.001）. Conclusion The plasma homocysteine level of IS patients was higher than that of healthy people. The mutation of MTHFR C677T and the declined level of folic acid and VitB12 may contribute to the elevation of homocysteine level. The MTHFR gene mutation may be irrelevant to ischemic stroke.