目的探讨支气管哮喘(哮喘)患儿亚甲基四氢叶酸还原酶(MTHFR)基因C677位点多态性与血清IgE水平的相关性。方法选择95例哮喘患儿作为病例组,均为急性发作期或临床缓解期哮喘患儿,患病前2周均未使用过肾上腺皮质激素及免疫调节剂。另选择健康儿童113例作为健康对照组。2组儿童年龄及性别比较差异均无统计学意义。采用PCR-限制性片段长度多态性分析法对病例组和健康对照组儿童外周血白细胞MTHFR基因C677位点基因多态性进行研究,应用双抗体夹心ELISA法检测2组儿童血清总IgE水平。结果健康对照组MTHFR 677C/T的3种基因型频率分别CC 35.4%、CT 45.1%、TT 19.5%,病例组分别为CC 24.2%、CT 40.0%、TT 35.8%,677C/T基因型分布频率在哮喘病例组和健康对照组间差异有统计学意义(χ2=7.556 5,P<0.05)。病例组T等位基因的频率为55.3%,健康对照组为42.0%,病例组较健康对照组显著增高,其患哮喘的危险度是健康对照组的1.71倍(χ2=7.254 7,P<0.01;95%CI:1.13～2.57)。病例组血清总IgE水平在各基因型患儿间比较差异有统计学意义(F=3.46,P<0.05),健康对照组血清总IgE水平在各基因型儿童间比较差异无统计学意义(F=0.13,P>0.05)。结论 MTHFRC677位点C→T的基因突变增加了患儿哮喘发病的危险度,TT基因型与哮喘的发生直接相关;哮喘患儿血清总IgE水平升高,该位点基因型并非导致血清总IgE水平升高的直接原因。 Objective To investigate the relationship between polymorphism of methylenetetrahydrofolate reductase (MTHFR) gene C677 and serum IgE in children with bronchial asthma (asthma). Methods Ninety-five children with asthma were selected as the cases, all of whom were children with asthma during acute attack or remission. None of them had been given adrenocorticotropic hormones and immunomodulators for two weeks. Another 113 healthy children were selected as healthy control group. There was no significant difference between the two groups in age and sex. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used to analyze the gene polymorphism of MTHFR gene C677 in children’s peripheral blood leucocytes and serum total IgE levels in both groups. Results The frequencies of MTHFR 677C / T genotypes were 35.4%, 45.1% and 19.5% respectively in MTHFR 677C / T patients. The frequencies of genotypes were 24.2% for CC, 40.0% for CT, 35.8% for TT, and 677C / T for T The difference between the asthma group and the healthy control group was statistically significant (χ2 = 7.556 5, P <0.05). The frequency of T allele was 55.3% in the case group and 42.0% in the healthy control group. The case group was significantly higher than the healthy control group, and the risk of asthma was 1.71 times of the healthy control group (χ2 = 7.254 7, P <0.01) ; 95% CI: 1.13 ~ 2.57). Serum total IgE levels in case group were significantly different among all genotypes (F = 3.46, P <0.05). There was no significant difference in serum total IgE levels among healthy children (F = 0.13, P> 0.05). Conclusion Mutation of C → T at MTHFRC677 increases the risk of asthma in children, TT genotype is directly related to the occurrence of asthma. Serum total IgE level in asthmatic children is elevated, and the genotype of this locus does not lead to the change of total serum IgE The direct cause of the level rise.