Institute of Clinical Medicine, National Yang-Ming University, School of Medicine, Taipei, Taiwan, ROC; Department of Pediatrics, Taipei Veterans General Hospital, Taipei, Taiwan, ROC.
Lanyu Township Health Office, Taitung, Taiwan, ROC.
Clin Nutr. 2015 Dec;34(6):1155-8. doi: 10.1016/j.clnu.2014.11.013. Epub 2014 Dec 3.
BACKGROUND & AIMS: Many studies have reported that serum total homocysteine (tHcy) levels in cystathionine-beta-synthase (CBS) carriers are usually normal and only elevated after a methionine load. However, the amount of methionine required for a loading test is non-physiological and is never reached with regular feeding. Therefore, CBS carriers do not seem to be at an increased risk of cardiovascular diseases. However, the risk of cardiovascular diseases of CBS carriers with folate deficiency has not been studied. We recently found an extraordinarily high carrier rate (1/7.78) of a novel CBS mutation (p.D47E, c.T141A) in an Austronesian Taiwanese Tao tribe who live in a geographic area with folate deficiency. We evaluated if the CBS carriers tend to have higher fasting serum tHcy concentrations than non-carriers in presence of folate deficiency.
The serum tHcy and folate levels before and after folate replacement were measured in 48 adult Tao carriers, 40 age-matched Tao non-carriers and 40 age-matched Han Taiwanese controls.
The serum tHcy level of the Tao CBS carriers (17.9 ± 3.8 μmol/l) was significantly higher than in Tao non-carriers (15.7 ± 3.5 μmol/l; p < 0.008) and Taiwanese controls (11.8 ± 2.9 μmol/l; p < 0.001). Furthermore, a high prevalence of folate deficiency in the Tao compared with the Taiwanese controls (4.9 ± 1.8 ng/ml vs. 10.6 ± 5.5 ng/ml; p < 0.001) was also noted. Of note, the difference in tHcy levels between the carriers and non-carriers was eliminated by folate supplementation. (carriers:13.65 ± 2.13 μmol/l; non-carriers:12.39 ± 3.25 μmol/l, p = 0.321).
CBS carriers tend to have a higher tHcy level in the presence of folate deficiency than non-carriers. Although many reports have indicated that CBS carriers are not associated with cardiovascular disease, the risk for CBS carriers with folate deficiency has not been well studied. Owing to a significantly elevated level of fasting tHcy without methionine loading, it is important to evaluate the risk of cardiovascular disease in CBS carriers with folate deficiency.
许多研究表明，胱硫醚-β-合酶（CBS）携带者的血清总同型半胱氨酸（tHcy）水平通常正常，仅在蛋氨酸负荷后升高。然而，负荷试验所需的蛋氨酸量是非生理的，并且在常规喂养中从未达到过。因此，CBS 携带者似乎不会增加患心血管疾病的风险。然而，叶酸缺乏症的 CBS 携带者患心血管疾病的风险尚未得到研究。我们最近在一个居住在叶酸缺乏地区的南岛语族台湾道族中发现了一种新型 CBS 突变（p.D47E，c.T141A）的异常高携带者率（1/7.78）。我们评估了在叶酸缺乏的情况下，CBS 携带者是否倾向于比非携带者具有更高的空腹血清 tHcy 浓度。
在 48 名成年道族携带者、40 名年龄匹配的道族非携带者和 40 名年龄匹配的台湾汉族对照组中，测量叶酸替代前后的血清 tHcy 和叶酸水平。
道族 CBS 携带者（17.9 ± 3.8 μmol/L）的血清 tHcy 水平明显高于道族非携带者（15.7 ± 3.5 μmol/L；p < 0.008）和台湾汉族对照组（11.8 ± 2.9 μmol/L；p < 0.001）。此外，与台湾汉族对照组相比，道族中叶酸缺乏症的患病率也很高（4.9 ± 1.8 ng/ml 比 10.6 ± 5.5 ng/ml；p < 0.001）。值得注意的是，叶酸补充消除了携带者和非携带者之间 tHcy 水平的差异。（携带者：13.65 ± 2.13 μmol/L；非携带者：12.39 ± 3.25 μmol/L，p = 0.321）。
在叶酸缺乏的情况下，CBS 携带者的 tHcy 水平往往高于非携带者。尽管许多报告表明 CBS 携带者与心血管疾病无关，但叶酸缺乏症的 CBS 携带者的风险尚未得到很好的研究。由于空腹 tHcy 水平明显升高而无需蛋氨酸负荷，因此评估叶酸缺乏症的 CBS 携带者患心血管疾病的风险很重要。
