方法：选取150例经压平眼压计、Humphrey 视野计(HVF)、光学相干断层扫描(optical coherence tomography，OCT)、房角镜等检查确诊为原发性闭角型青光眼(primary angle-closure glaucoma，PACG)的患者作为试验组和同期150例我院体检中心健康者为正常对照组，抽取空腹外周静脉血，而后测定血浆中同型半胱氨酸(homocysteine，Hcy)浓度、维生素B12及叶酸的浓度，并提取DNA，检测Hcy代谢途径中关键酶——亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase，MTHFR)C677T的基因型及基因多态性。

结果：试验组血浆中Hcy的浓度为16.11±1.66μmol/L，正常对照组为15.74±1.52μmol/L，两组比较，差异有统计学意义(t=2.04，P=0.04)。试验组血浆中维生素B12的浓度为248.09±119.07pg/mL，正常对照组为230.21±142.93pg/mL，两组比较差异无统计学意义(t=0.84，P=0.40)。试验组血浆中叶酸的浓度为12.02±7.81ng/mL，正常对照组为13.15±6.25ng/mL，两组比较差异无统计学意义(t=1.65，P=0.17)。试验组MTHFR C677T基因型(CC、CT、TT)分布频率分别84.7%、4.7%、10.7%，正常对照组分别为94.7%、2.0%、3.3%，两组基因型分布频率差异具有统计学意义(χ²=6.2，P<0.05)； 其中试验组MTHFR基因TT纯合子的分布频率高于正常对照组； 试验组MTHFR基因T、C等位基因频率分别为87.0%、13.0%，正常对照组为95.7%、4.3%，两组差异具有统计学意义(χ²=14.2，P<0.05)。

结论：PACG患者血浆中Hcy的浓度及MTHFR基因型TT纯合子的分布频率高于正常对照组，说明高Hcy水平及其代谢相关因素可能与PACG的发病与发展密切相关。

METHODS: In this study, a total of 150 PACG patients and 150 controls were enrolled. The patients with PACG were diagnosed by applanation tonometer, Humphrey perimetry(HVF), optical coherence tomography(OCT), gonioscope. The normal controls were recruited from physical examination center. Blood samples were collected and the plasma was used to determine homocysteine, vitamin B12 and folic acid. DNA was extracted to determine the methylenetetrahydrofolate reductase(MTHFR)C677TT genotype and gene polymorphism.

RESULTS: There was a statistically significant difference(t=2.04,P=0.04)in mean homocysteine levels between patients with PACG(16.11±1.66μmol/L)and controls(15.74±1.52μmol/L). The level of vitamin B12 in PACG group was 248.09±119.07pg/mL and the control group was 230.21±142.93pg/mL. No statistically significant difference was found on the vitamin B12 level between the two groups(t=0.84,P=0.40). The folic acid levels showed no statistically significant differences(t=1.65,P=0.17)between the PACG group(12.02±7.81ng/mL)and the control group(13.15±6.25ng/mL). The frequency distribution of the MTHFR C677T genotypes was found to be significantly associated(χ²=6.2,P<0.05)with PCAG(CC 84.7%, CT 4.7%, TT 10.7%)as compared to the controls(CC 94.7%, CT 2.0%, TT 3.3%). The frequency distribution of TT genotypes of MTHFR C677T in the PACG group was significantly higher than that in the control group. Moreover, our findings showed significant difference(χ²=14.2,P<0.05)between the allele frequency of the C677T single nucleotide polymorphism within the MTHFR gene in POAG patients(T 87.0%, C 13.0%)and the control group(T 95.7%,C 4.3%).

CONCLUSION: These results show that the Hcy level and the TT genotypes of MTHFR C677T were higher in the PACG patients than in controls. Therefore, our data suggests that high Hcy level and the related indicators are associated with high PACG risk.