在中国等低叶酸人群中，叶酸与预防中风的相关性尚不确定。亚甲基四氢叶酸还原酶 (MTHFR) C677T 多态性会增加血浆同型半胱氨酸 (tHcy) 水平，对其进行遗传学研究可以阐明未叶酸强化人群中 tHcy 水平升高与中风、缺血性心脏病 (IHD) 和其他疾病的因果关系。前瞻性的中国嘉道理生物银行对 156±253 名参与者进行了 MTHFR 基因分型，并在 12 年的随访期间，有 12±240 名参与者患上了中风。使用 Logistic 回归来估计总中风和中风类型、IHD 和其他疾病的区域特异性比值比 (OR)，比较 MTHFR C677T 的 TT 基因型（MTHFR C677T 多态性第 677 位的两个胸腺嘧啶等位基因）与 CC（两个胞嘧啶等位基因）调整年龄和性别后，使用逆方差权重将这些数据合并起来。总体而言，21% 的参与者具有 TT 基因型，但在 10 个研究区域中这一比例从 5% 到 41% 不等。具有 TT 基因型的个体发生任何中风的风险高出 13%（调整后 OR 1.13，95% CI 1.09-1.17）[与脑内出血的相关性（1.24，1.17-1.32）比缺血性中风（1.11，1.07）强 2 倍-1.15)]比参考CC基因型。相比之下，MTHFR C677T 与 IHD 或任何其他非血管疾病（包括癌症、糖尿病和慢性阻塞性肺病）的风险无关。在中国成年人中，MTHFR C677T 多态性与较高的中风风险相关。这些发现值得通过进一步的叶酸试验和实施强制性叶酸强化计划来证实，以预防低叶酸人群中风。© 作者 2023。由牛津大学出版社代表国际流行病学协会出版。

The relevance of folic acid for stroke prevention in low-folate populations such as in China is uncertain. Genetic studies of the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism, which increases plasma homocysteine (tHcy) levels, could clarify the causal relevance of elevated tHcy levels for stroke, ischaemic heart disease (IHD) and other diseases in populations without folic acid fortification.In the prospective China Kadoorie Biobank, 156 253 participants were genotyped for MTHFR and 12 240 developed a stroke during the 12-year follow-up. Logistic regression was used to estimate region-specific odds ratios (ORs) for total stroke and stroke types, IHD and other diseases comparing TT genotype for MTHFR C677T (two thymine alleles at position 677 of MTHFR C677T polymorphism) vs CC (two cytosine alleles) after adjustment for age and sex, and these were combined using inverse-variance weighting.Overall, 21% of participants had TT genotypes, but this varied from 5% to 41% across the 10 study regions. Individuals with TT genotypes had 13% (adjusted OR 1.13, 95% CI 1.09-1.17) higher risks of any stroke [with a 2-fold stronger association with intracerebral haemorrhage (1.24, 1.17-1.32) than for ischaemic stroke (1.11, 1.07-1.15)] than the reference CC genotype. In contrast, MTHFR C677T was unrelated to risk of IHD or any other non-vascular diseases, including cancer, diabetes and chronic obstructive lung disease.In Chinese adults, the MTHFR C677T polymorphism was associated with higher risks of stroke. The findings warrant corroboration by further trials of folic acid and implementation of mandatory folic acid fortification programmes for stroke prevention in low-folate populations.© The Author(s) 2023. Published by Oxford University Press on behalf of the International Epidemiological Association.