慢性肾衰竭血透患者N^5,N^(10)-亚甲基四氢叶酸还原酶基因多态性和血浆同型半胱氨酸水平的研究

Methylenetetrahydrofolate reductase gene polymorphism and plasma homocysteine levels in hemodialysing patients

目的 研究血透患者N5,N10 亚甲基四氢叶酸还原酶 (MTHFR)基因多态性及血清叶酸、维生素B12 (VitB12 )水平与血浆总同型半胱氨酸 (tHcy)的关系。方法 运用聚合酶链反应 限制性内切酶片断长度多态性技术 (PCR RFLP) ,检测 5 3例血透患者 (HD组 )及 4 0例健康对照组 (C组 )的MTHFR基因多态性 ;用高效液相色谱法和荧光探测仪测定血浆tHcy水平 ;用免疫化学发光法测定血清叶酸、VitB12 水平。结果 (1)MTHFR基因型有 3种 ,纯合子突变型 (+/ +)、杂合子突变型(+/ - )、正常型 (- / - )。HD组中 (+/ +)型频率为 30 2 % ,(+/ - )型频率为 4 5 3% ,(- / - )型频率为 2 4 5 % ,T等位基因频率为 5 2 8% ,基因型分布和等位基因频率与C组比较差异无显著性。 (2 )HD组中 98%的患者存在着高Hcy (>15 0 μmol/L)血症 ,平均血浆tHcy水平显著高于C组 (38 6 8μmol/L对 15 4 7μmol/L ,P <0 0 1)。 (3)HD组中 (+/ +)型平均血浆tHcy水平高于 (- / - )型 (45 32μmol/L对 2 8 4 4 μmol/L) ,两者差异具有显著性 (P =0 0 38)。 (4)HD组血清叶酸、VitB12 均与血浆tHcy水平呈负相关 (r=- 0 377,P =0 0 0 5 ;r =- 0 311,P =0 0 2 3)。结论 血透患者血浆tHcy水平升高不仅与患者尿毒症时对其清除及代谢障碍有关 ,?

Objective To study the influence of mutation of 677 C to T in the methylenetetrahydrofolate reductase (MTHFR) gene on the plasma total homocysteine (tHcy) levels in hemodialysis patients Methods The study population included 40 healthy subjects and 53 patients with end stage renal disease (ESRD) undergoing hemodialysis C 677 T transition in the MTHFR gene was detected by Hinf 1 restriction enzyme analysis Plasma tHcy concentrations were determined by HPLC with fluorescent detection Serum folate and vitamin B 12 levels were measured with chemiluminescent immunoassay Results The allelic frequency of the 677 C to T transition in the MTHFR gene in hemodialysis patients was 52 8% versus 53 8% in healthy controls The mean tHcy level was significantly higher in hemodialysis patients than that in control subjects (38 68 μmol/L versus 15 47 μmol/L, P < 0 01) The folate and vitamin B 12 concentrations were higher in patients than those in controls There was a significant influence of the +/+ genotype, folate and vitamin B 12 status on plasma tHcy level Conclusion It is demonstrated that the extent of hyperhomocysteinemia in hemodialysis patients is not only the result of impaired metabolism and elimination of Hcy in uremia, but is also genetically determined by the MTHFR genotype Folate and vitamin B 12 status also influences the homocysteine concentration of hemodialysis patients