目的：探讨亚甲基四氢叶酸还原酶（MTHFR）基因C677T单核苷酸多态性（SNP）与腹腔静脉血栓（SVT）易感性的关联情况。方法：检索多个国内外数据库收集MTHFR C677T SNP与SVT相关的病例-对照研究，用Stata 12.0软件分析其基因型和等位基因与SVT的关联性。结果：共纳入19篇文献，包括1 194例患者和1 988例对照。SVT分为门静脉血栓（PVT）、Budd-Chiari综合征（BCS）和肠系膜静脉血栓（MVT）3个亚组。MTHFR C677T SNP在显性模型CC vs. （CT+TT）下（OR=0.51，95% CI=0.34~0.76，P=0.001）和相加模型CC vs. TT下（OR=0.33，95% CI=0.23~0.47，P<0.001）与SVT的关联性有统计学意义；在隐性模型TT vs.（CT+CC）下，MTHFR C677T SNP与SVT（OR=2.27，95% CI=1.77~2.90，P<0.001）及PVT亚组（OR=2.23，95% CI=1.57~3.17，P<0.001）的关联性有统计学意义；在等位基因模型T vs. C下，MTHFR C677T SNP与SVT（OR=1.84，95% CI=1.33~2.55，P<0.001）及MVT亚组（OR=1.64，95% CI=1.14~2.36，P=0.008）的关联性有统计学意义。结论：MTHFR C677T SNP与SVT易感性之间有关联性，携有TT基因型和T等位基因的人群罹患SVT的风险可能增加。
Association between single nucleotide polymorphisms at C677T of methylenetetrahydrofolate reductase gene and susceptibility to splanchnic vein thrombosis: a Meta-analysis
Objective: To investigate the association between single nucleotide polymorphisms (SNPs) at C677T of methylenetetrahydrofolate reductase (MTHFR) gene and susceptibility to splanchnic vein thrombosis (SVT). Methods: The relevant case-control studies regarding MTHFR C677T SNPs and SVT were collected by searching several national and international online databases. The associations of the genotypes and allelic genes of MTHFR with SVT were analyzed by Stata 12.0 software. Results: Nineteen studies were finally included involving 1 194 SVT patients and 1 988 control subjects. SVT were divided into 3 subgroups: portal vein thrombosis (PVT), Budd-Chiari syndrome (BCS) and mesenteric vein thrombosis (MVT). MTHFR C677T SNPs were significantly associated with SVT under dominant model CC vs. (CT+TT) (OR=0.51, 95% CI=0.34–0.76, P=0.001) and additive model CC vs. TT (OR=0.33, 95% CI=0.23–0.47, P<0.001); MTHFR C677T SNPs were significantly associated with SVT (OR=2.27, 95% CI=1.77–2.90, P<0.001) and PVT subgroup (OR=2.23, 95% CI=1.57–3.17, P<0.001) under recessive model TT vs. (CT+CC); MTHFR C677T SNPs were significantly associated with SVT (OR=1.84, 95% CI=1.33–2.55, P<0.001) and MVT subgroup (OR=1.64, 95% CI=1.14–2.36, P=0.008) under allele gene model. Conclusion: There is an association between MTHFR C677T SNPs and SVT susceptibility, and those with TT genotype and T alleles may have increased risk of SVT.