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A.G. Junemann, N. von Ahsen, J. Kornhuber, K. Ritter, G.O. Naumann, S. Bleich; MTHFR C677T Polymorphism Is a Genetic Risk Factor for Primary Open-Angle Glaucoma . Invest. Ophthalmol. Vis. Sci. 2003;44(13):93.
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Purpose:Homocysteine can induce alterations in extracellular matrix and neuronal cell death that are characteristic findings in glaucoma. Moderate hyperhomocysteinaemia has been related to genetic or non-genetic risk factors. Homozygous or heterozygous thermolabile methylenetetrahydrofolate reductase (MTHFR) deficiency are the most common etiological factors to cause moderate hyperhomocysteinaemia. This study was performed to determine the prevalence of thermolabile MTHFR C677T variant in patients with primary open-angle glaucoma (POAG) and secondary open-angle glaucoma (SOAG) due to pseudoexfoliation. Methods:Total plasma homocysteine, vitamins relevant in its metabolism (folate, B12, B6), and genotyping for the thermolabile MTHFR variant (C677T) were determined in patients with POAG (n=18), SOAG (n=19), and 19 controls with cataracts. Patients with any commonly known other risk factors for hyperhomocysteinemia were excluded. Making the groups maximally comparable controls were matched to cases by age, gender and concurrent diagnosis of systemic hypertension. Results:Significantly raised plasma homocysteine levels were found in patients with POAG (12.52µmol/l ± 3.62, U = 30, P < 0.001) and SOAG (11.61µmol/l ± 3.74, U = 63, P < 0.001) when compared with the control group (8.40µmol/l ± 1.74). Furthermore, we observed a significantly higher prevalence of the MTHFR C677T polymorphism in patients with POAG (11.1% homozygous, 61.1% heterozygous) (P = 0.022, OR 5.34, 95%-CI 1.14-29.56) when compared with the control group (5.3% homozygous, 26.3% heterozygous). In contrast, the MTHFR prevalence in patients with SOAG (5.3% versus 36.8%, respectively) was not increased significantly (P > 0.05, OR 1.56, 95%-CI 0.35-7.37). Other characteristics between patients and controls such as vitamin levels (folate, B12, B6) were not changed. Conclusions:The present study revealed elevated homocysteine levels in patients with POAG and SOAG. Furthermore, a high prevalence of the C677T polymorphism in patients with POAG was found. Therefore, increased levels of homocysteine due to a high prevalence of MTHFR C677T polymorphism in patients with POAG may have important implications for understanding the pathogenesis of glaucomatous optic neuropathy.
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