The effect of MTHFR ala222val polymorphism on open-angle glaucoma: a meta-analysis

Correlation between MTHFR polymorphisms and glaucoma: A meta-analysis

Background

Whether methylenetetrahydrofolate reductase (MTHFR) polymorphisms are implicated in glaucoma remains controversial. Therefore, we performed this study to better assess the relationship between MTHFR polymorphisms and the likelihood of glaucoma.

Methods

A systematic research of PubMed, Medline, and Embase was performed to retrieve relevant articles. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated.

Results

A total of 18 studies with 7,168 participants were analyzed. In overall analyses, a significant association with the likelihood of glaucoma was detected for the rs1801133 polymorphism in dominant (p = 0.04, OR = 0.90, 95%CI 0.81–1.00) and allele (p = 0.02, OR = 0.91, 95%CI 0.84–0.98) comparisons. Further, subgroup analyses by ethnicity revealed that both rs1801131 and rs1801133 polymorphisms were significantly associated with the likelihood of glaucoma in West Asians. However, no positive results were detected for two investigated polymorphisms in East Asians and Caucasians.

Conclusion

Our findings indicated that rs1801131 and rs1801133 polymorphisms may serve as genetic biomarkers of glaucoma in West Asians.

miR‑17‑5p regulates the proliferation and apoptosis of human trabecular meshwork cells by targeting phosphatase and tensin homolog

Glaucoma is one of the leading causes of blindness. Previous studies have indicated that the oxidative stress-induced apoptosis of trabecular meshwork cells (TMCs) may serve a key role in the pathogenesis of glaucoma, and that micro RNA(miR)-17-5p may be involved in this process. However, the specific mechanisms require further investigation. The aim of the present study was to investigate the effects of miR-17-5p on the proliferation and apoptosis of human TMCs (HTMCs) in response to oxidative stress. It was observed that exposure to H₂O₂ induced a significant decrease in the proliferation and a marked increase in the apoptosis of HTMCs. H₂O₂ exposure also suppressed the expression of miR-17-5p and promoted the expression of phosphatase and tensin homolog (PTEN). Furthermore, transient overexpression of miR-17-5p induced a significant increase in the proliferation and a significant decrease in the apoptosis of HTMCs by affecting the expression of PTEN, and the apoptosis-related proteins B-cell lymphoma-associated X protein (Bax), B-cell lymphoma-extra large (Bcl-xL) and B-cell lymphoma-2 (Bcl-2). However, knockdown of miR-17-5p demonstrated the opposite results. The results of a dual luciferase reporter assay demonstrated that PTEN may be a direct target of miR-17-5p. In conclusion, miR-17-5p was downregulated in HTMCs under oxidative conditions, and miR-17-5p may regulate the apoptosis of HTMCs by targeting PTEN. These results provide a novel theoretical basis and potential therapeutic target for the treatment of glaucoma.

Association of the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism with primary glaucoma in Saudi population

Background

Methylenetetrahydrofolate reductase (MTHFR), a critical enzyme in folate metabolism is involved in DNA synthesis, DNA repair and DNA methylation. The functional polymorphism of MTHFR gene, C677T has been shown to impact various diseases and implicated as a risk factor for the development of various neurodegenerative disorders including glaucoma.

Methods

We investigated MTHFR C677T genotypes and alleles frequencies in primary glaucoma [primary open angle glaucoma (POAG) and primary angle closure glaucoma (PACG)] patients and matched healthy controls in a case-control study. Two hundred ten primary glaucoma cases were studied for MTHFR C677T polymorphism and compared with 280 controls taken from the healthy population, employing the polymerase chain reaction-restriction fragment length polymorphism technique (PCR-RFLP). The MTHFR gene was amplified using specific primers. The PCR products (294 bp) was subsequently digested with HinfI (New England Biolabs) at 37 °C for 12 h, separated by electrophoresis on 2 % agarose gels, and visualized with ethidium bromide staining. The restriction digestion yielded 168 and 126 bp fragments for TT, 294, 168 and 126 bp fragments for CT and undigested PCR product 294 bp indicating CC genotype.

Results

We found the frequency of the genotypes and alleles of MTHFR C677T differ significantly between cases and controls. The frequencies of allele T and genotype CT were significantly higher while the frequencies of allele C and genotype CC were lower in primary glaucoma patients as compared to controls (p <0.05). Upon stratification of our results into POAG and PACG, significantly higher frequencies of allele T (19.44 %) and genotype CT (38.89 %) were found in POAG patients compared to controls (12.5 % and 25 % respectively). The frequencies of alleles and genotypes were almost similar in PACG and controls (p = 0.8).

Conclusion

This study indicates that the allele T and genotype CT of MTHFR C677T polymorphism are significantly associated with POAG while allele C and CC genotype may be protective for it. We conclude that the MTHFR C677T polymorphism increases the risk for POAG development in Saudi population and can be a genetic marker however, further studies are needed with multiple-ethnic populations affected with POAG to strengthen these findings.