Association study of high-frequency variants of MTHFR gene with retinal vein occlusion in a Spanish population

Combination Therapy with Anti-VEGF and Intravitreal Dexamethasone Implant for Macular Edema Secondary to Retinal Vein Occlusion

PURPOSE

To compare the safety and efficacy of intravitreal injection of ranibizumab alone or ranibizumab combined with dexamethasone intravitreal implant in the treatment of macular edema secondary to retinal vein occlusion.

STUDY DESIGN

A single center, case-controlled, prospective cohort study (Clinical Trail Registration Number: ChiCTR2400080048).

METHODS

A total of 44 patients were enrolled and randomized into the ranibizumab group (n = 23) and the combination group (ranibizumab combined with dexamethasone intravitreal implant) (n = 21). All patients received ranibizumab intravitreal injections in the first three months as the initial treatment. For the ranibizumab group, patients might receive repeat injections in case of the recurrence of macular edema; For the combination group, patients received an intravitreal injection of dexamethasone implant after the first injection of ranibizumab at the day 15. The main outcome was best-corrected visual acuity (BCVA) and reduction of central macular thickness. The secondary outcome were the numbers of recurrence, the average injection interval, and the numbers of injection. Adverse events were also recorded.

RESULTS

The BCVAs in both groups were significantly improved compared with the baselines (all p < 0.001), but more increment in BCVA was noticed at the 3-month in the combination group (p = 0.022). Both groups showed a reduction of central macular thickness at all time points (p < 0.05). However, the combination group did not exhibit higher central macular thickness-reducing effects than the ranibizumab group (p > 0.05). Compared with the combination group, the ranibizumab group suffered a higher number of recurrences of macular edema (p < 0.001), a lower interval of injection (p = 0.050), and a higher number of injection (p < 0.011). The incidence of adverse events was not significant between the two groups (p = 0.944).

CONCLUSIONS

Ranibizumab combined with dexamethasone injection sustainably improved the BCVA of retinal vein occlusion patients with a good safety profile.

Methylenetetrahydrofolate reductase polymorphisms as risk factors for retinal venous occlusive disease: A literature review

The role of polymorphisms of methylenetetrahydrofolate reductase (MTHFR) gene in retinal vein occlusion (RVO) is a theme of discussion since the first reports of RVO in patients with MTHFR C677T mutation and without classic acquired risk factors for retinal vascular disease. The association between MTHFR polymorphisms and RVO has been studied over the last 20 years producing conflicting results. This review aims to summarize the literature concerning the role MTHFR polymorphisms as risk factors for RVO.

Association Study of MTHFR Polymorphisms with Nonarteritic Anterior Ischemic Optic Neuropathy in a Spanish Population

Introduction

Nonarteritic anterior ischemic optic neuropathy (NAION), painless loss of central and/or peripheral vision, is a multifactorial disease caused by insufficient blood flow through the posterior ciliary arteries to the optic nerve head. Mutations in the methylenetetrahydrofolate reductase (MTHFR) gene, triggering hyperhomocysteinemia as a consequence of a decreased activity of the codified enzyme, have been considered to be among the risk factors of NAION.

Objective

The main aim was to study the association of the most common MTHFR genetic polymorphisms C677T and A1298C with NAION in a Spanish population.

Methods

In this case-control study, the association of the most common MTHFR polymorphisms was investigated in 94 unrelated native Spanish patients diagnosed with NAION and 204 healthy controls. Two single nucleotide polymorphisms located in the MTHFR gene, C677T (rs1801133) and A1298C (rs1801131), were analyzed by DNA sequencing and TaqMan assays.

Results

The allelic and genotypic frequencies of the MTHFR variants obtained in the NAION group were not significantly different when compared with the control group. A higher frequency of the C677T/A1298C genotype, codifying the nonmutated MTHFR form, was obtained in control subjects (11.27%) compared to NAION patients (4.26%), suggesting a protective effect of the wild-type protein, although this result was not conclusive considering the obtained confidence interval (CI) (95% CI: 0.13-1.06). Study of additional clinical factors including hypertension, diabetes mellitus, and dyslipidemia showed no association with a higher risk of NAION. Conversely, the clinical history of heart or cerebrovascular diseases was significantly higher in NAION patients compared to controls. Over the world, risk variants of the MTHFR gene are highly frequent, excluding African black populations, indicating a racial influence.

Conclusions

The MTHFR variants did not significantly increase the risk of suffering from NAION. However, considering that individuals with at least one of the risk variants have the MTHFR enzyme with decreased activity, it cannot be ruled out that these mutations are relevant for the development of NAION in a subgroup of the population with other specific characteristics. These may include high plasma levels of homocysteine along with nutritional deficiencies including low folate or vitamin B12 and the combination of systemic and local risk factors.

Diabetes mellitus as a risk factor for retinal vein occlusion: A meta-analysis

Retinal vein occlusion (RVO) is the second most common etiology for vision loss. There is contrasting evidence on the association between diabetes mellitus (DM) and the risk of RVO. We performed a meta-analysis of published articles before October 31, 2019, to estimate a pooled odds ratio for the association between DM and RVO, including central and branch RVO by a fixed or random effects model. We identified 37 publications from 38 studies (1 publication was from 2 studies), published between 1985 and 2019. In total, 148,654 cases and 23,768,820 controls were included in this meta-analysis. The results of pooled analysis for all 37 publications (or 38 studies) showed a significant association between DM and the risk of RVO (OR = 1.68, 95% CI: 1.43-1.99). Subgroup analysis indicated that DM was significantly associated with CRVO (OR = 1.98, 95% CI: 1.29-3.03, I = 67.9%), but not significantly associated with BRVO (OR = 1.22, 95% CI: 0.95-1.56, I = 64.1%). In conclusion, the result of present meta-analysis suggested that DM is a risk factor for RVO. More well-designed studies on the relationship between RVO and DM should be undertaken in the future.