目的：心脏圆锥动脉干缺损(CTD)是一组严重的、复杂的青紫型先天性心脏病。N5, 10 亚甲基四氢叶酸还原酶(MTHFR)是参与甲硫氨酸-叶酸代谢的关键酶,其基因677位点C→T错义突变可造成此酶活性降低,导致高同型半胱氨酸血症,现已证明高同型半胱氨酸是诱发胎儿出生缺陷和心血管疾病的一个独立危险因素。本研究旨在了解中国CTD患儿MTHFR基因C677T位点突变的情况。方法：用多聚酶链反应限制性内切酶片段长度多态性技术(PCR RFLP)检测97例CTD患儿和118例正常健康人MTHFR基因677位点C→T突变多态性,并比较两组677TT的纯合突变率。结果：CTD患儿中TT基因型频率为24. 7% (24 /97),显著高于对照组13. 6%,χ2 = 4. 40,P= 0. 036,OR值2. 1(95% CI: 1. 04~4. 22);CTD患儿组T等位基因频率为52. 6%,显著高于对照组42. 8%,χ2 = 4. 09, P= 0. 043,OR值1. 5(95% CI: 1. 01~2. 17)。其中法洛氏四联症、主动脉缩窄、主动脉弓离断的TT基因型频率为29. 7% ~40. 0%。结论：MTHFR基因与心脏圆锥动脉干缺损有一定关系,其677TT基因型可能是引起先天性心脏畸形的危险因素之一。

OBJECTIVE: To explore the role of 5,10-methylenetetrahydrofolate reductase (MTHER) C677T polymorphisms in Chinese children with conotruncal heart defects (CTD). METHODS: A total of 97 children with CTD and 118 healthy controls were recruited into the study. MTHER genetic C677T polymorphisms were determined by PCR-RFLP. The 677TT genotype was compared between the two groups. RESULTS: The frequency of the TT genotype and T allele in CTD patients was 24.7% and 52.6%, respectively, which was significantly higher than that of controls ( 13.6% and 42.8%) (P = 0.036, P = 0.043, respectively). In patients with tetralogy of Fallot, coarctation of aorta or interruption of aortic arch, the frequency of the TT genotype varied between 29.7% and 40.0%. CONCLUSIONS: MTHFR gene is associated with CTD, and 677TT genotype might be a risk factor for congenital heart malformations.