Hyperhomocysteinemia and the methylenetetrahydrofolate reductase 677C-T mutation in patients under 50 years of age affected by central retinal vein occlusion

Hemicentral retinal vein occlusion in a patient with a history of coronavirus disease 2019 infection: a case report and review of the literature

BACKGROUND

Considering the various manifestations of coronavirus disease 2019 and its imperative importance in terms of the right clinical approach and early management, we sought to present a hemicentral retinal vein occlusion case, with a history of heterozygosity of methylenetetrahydrofolate reductase (MTHFR) genes and potential for clotting complications as a late manifestation of coronavirus disease 2019, and provide a brief review of reported retinal vein occlusion cases in patients with coronavirus disease 2019.

CASE PRESENTATION

A 35-year-old Iranian patient presented with a visual impairment in the left eye 4 months after recovering from coronavirus disease 2019. He reported a mild blurring of vision in the same eye a few days after admission due to coronavirus disease 2019. The ophthalmic evaluation was compatible with hemicentral retinal vein occlusion. Systemic and laboratory workups were negative except for borderline protein C activity, homocysteine levels, and heterozygosity of MTHFR genes. The patient was scheduled to receive three monthly intravitreal antivascular endothelial growth factor injections.

CONCLUSION

We present a case of inferior hemicentral retinal vein occlusion case with an MTHFR mutation with sequential loss of vision 4 months after coronavirus disease 2019 to make clinicians aware of the possibility of late ocular coronavirus disease 2019 manifestations.

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.

Ranibizumab for Macular Edema Secondary to Central and Branch Retinal Vein Occlusion in Patients Younger Than 50 Years of Age

Background

To determine the effectiveness of intravitreal ranibizumab (IVR) approach over 1-year follow-up in patients younger than 50 years old with central and branch retinal vein occlusion (RVO) complicated by macular edema (ME).

Methods

Prospective, open-label case series. Patients initiating IVR injections from January 2015 to May 2017 were consecutively recruited. Each patient underwent monthly ophthalmic examination and structural OCT over 12 months. A single IVR injection was administered at baseline, followed by a PRN regimen. Outcome measures are best-corrected visual acuity (BCVA); central foveal thickness (CFT); number of IVR injections; subretinal fluid (SRF); epiretinal membrane; and outer retinal layer (ORL) status.

Results

Thirty-eight patients (27 males) were included in the study. At follow-up, mean BCVA improved from 0.40 ± 0.17 to 0.10 ± 0.10 LogMAR in patients with central RVO and from 0.39 ± 0.19 to 0.19 ± 0.07 LogMAR in those with branch RVO, with 20 eyes gaining ≥3 ETDRS lines. In addition, mean CFT significantly decreased in both subgroups at the end of follow-up. All patients with SRF at baseline (9) disclosed complete resolution after 1 year. Likewise, ORL appeared reconstituted in most cases. At 12 months, 3.6 ± 2.4 and 4.4 ± 2.4 IVR injections were required for central and branch RVO, respectively, with only 5 eyes showing ME persistence.

Conclusions

Our study indicates that IVR injections can be a valid therapeutic option in patients under 50 years of age with ME secondary to RVO.

Central Retinal Vein Occlusion in Younger Swedish Adults: Case Reports and Review of the Literature

Purpose:

To investigate associated systemic diseases, other conditions, visual outcome, ocular complications and treatment in Swedish patients younger than 50 years with central retinal vein occlusion (CRVO) and reviewing the literature.

Methods:

Twenty-two patients with CRVO, younger than 50 years, were examined with full-field electroretinography (ERG) within 3 months after a thrombotic event, or were periodically examined and were observed for at least 6 months. In 18 of these patients, the initial retinal ischemia was studied using the cone b-wave implicit time in the 30 Hz flicker ERG. Fifteen patients also underwent fluorescein angiography. Optical coherence tomography (OCT) was performed in 14 patients. The patients studied were divided into two groups, non-ischemic and ischemic, which were compared. All patients underwent ocular and systemic examination, as well as complete screening for thrombophilic risk factors.

Results:

Of the 22 patients, 15 had non-ischemic type of CRVO and 7 the ischemic type. Patients with non-ischemic CRVO showed significantly improved visual acuity (VA) at the final examination (p=0.006). Patients with ischemic CRVO showed no significant reduction in VA at the final examination (p=0.225). Systemic hypertension (27% in non-ischemic CRVO and 29% in ischemic CRVO) was the most prevalent systemic risk factor for CRVO. The mean central foveal thickness (CFT) decreased significantly from 402.3±136.2 (µm) at the initial examination to 243.8±48.1 (µm) at the final examination in the non-ischemic group (p=0.005). The mean initial CFT was 444.5±186.1 (µm) in the ischemic CRVO group, which decreased to 211.5±20.2 (µm) at the final visit (p=0.068). Pigment dispersion syndrome (PDS)/pigmentary glaucoma (PG), ocular hypertension and dehydration were equally frequent; four patients each (18%) out of 22. The clinical course of 4 younger patients with PDS/PG are described.

Conclusion:

The patients with non-ischemic CRVO showed significantly improved VA and significantly decreased CFT at the final examination. Systemic hypertension was the most prevalent risk factor for CRVO. Younger adults with CRVO also had a high prevalence of PDS/PG, ocular hypertension and dehydration. This study highlights the importance of careful IOP monitoring, and the need to investigate possible PDS/PG and to obtain an accurate history of the patient including alcohol intake and intense exercise.

Hyperhomocysteinia is a risk factor for retinal venous occlusion: a case control study

BACKGROUND

We evaluated the role of hyperhomocysteinemia as a risk factor for retinal vein occlusion (RVO) in Indian patients.

TYPE OF STUDY

Matched case control type of longitudinal study was conducted in 2006-2007.

MATERIALS AND METHODS

Two medical retina specialists examined the eyes having an event of RVO in the last 15 days. A similar number of eyes without RVO were also examined. The serum and urine homocysteine levels of these persons were tested. Matched pair analysis was carried out to determine the risk of RVO among those with hyperhomocysteinemia.

RESULTS

We included 20 cases of RVO and 20 age- and sex-matched persons without RVO. The risk of RVO was significantly higher in persons with hyperhomocysteinemia [difference of mean 31.62 μmol/L (95% Confidence Interval 16.60-47 . 86), P = 2.1 × 10-13 ]. The mean urine homocysteine level among cases and controls was not statistically significant. There were 12 persons with hypertension in both cases and control groups.

CONCLUSION

Hyperhomocysteinemia is a risk factor for RVO. Any list of investigations for a case of RVO should include total plasma homocysteine (tHcy) levels.

Plasma homocysteine in patients with retinal vein occlusion

PURPOSE

To evaluate total plasma homocysteine (HCY) during fasting and post methionine load test (MLT), serum folate, serum vitamin B12, and methylenetetrahydrofolate reductase (MTHFR) mutation in patients with retinal vein occlusion (RVO) and to examine the association between these risk factors and 2 subtypes of RVO: central (CRVO) and branch (BRVO).

METHODS

This case-control study included 91 Italian patients presenting a first RVO and 71 healthy subjects, matched by age, without history of thromboembolic diseases, glaucoma, or malignancy. Homocysteine fasting and after MLT, serum folate level, serum vitamin B12 level, and other laboratory tests were assessed. Genetic analysis for the C677T MTHFR mutation was performed.

RESULTS

Multivariate logistic regression analysis indicated that hypertension (odds ratio [OR] 2.63; 95% confidence interval [CI] 1.30-5.30; p = 0.007), higher values of fasting HCY (OR 1.16; 95% CI 1.01-1.33; p = 0.03), and low concentrations of vitamin B12 (OR 0.99; 95% CI 0.995-0.999; p = 0.01) were independently correlated with RVO. Moreover, the main determinants for CRVO risk were hypertension (OR 2.46; 95% CI 1.06-5.72; p = 0.04), high values of fasting HCY (OR 1.20; 95% CI 1.02-1.41; p = 0.03), and low concentrations of vitamin B12 (OR 0.99; 95% CI 0.994-0.999; p = 0.008), whereas for BRVO risk only hypertension was significant (OR 2.74; 95% CI 1.24-6.03; p = 0.01). Genotype distribution of the MTHFR C677T mutation did not reveal any significant difference between patients and controls.

CONCLUSIONS

These results suggest that elevated fasting HCY levels, low vitamin B12 levels, and hypertension are associated with a risk of RVO, especially for CRVO. Moreover, our data suggest that only hypertension is associated with BRVO risk.

Genetic polymorphisms associated with retinal vein occlusion: a Greek case-control study and meta-analysis

BACKGROUND

The genetic background of retinal vein occlusion (RVO) remains unclear. In the current study, we aimed to replicate polymorphisms related to thrombophilia/hypofibrinolysis in a Greek population and also systematically summarize current evidence available on the topic.

MATERIALS AND METHODS

A total of 48 RVO patients and 53 controls were genotyped for factor V H1299R and V Leiden, β-fibrinogen G455A, PAI-1 4G/5G, ACE I/D, HPA1, prothrombin G20210A, factor XIII Val34Leu, MTHFR A1298C and C677T polymorphisms. We examined the association between RVO and the above polymorphisms under a per-allele genetic model in a Greek unrelated case/control population. Additionally, searching PubMed up to January 2012, we identified existing evidence on these polymorphisms and performed meta-analyses.

RESULTS

A total of three polymorphisms had nominally significant associations with RVO. These associations pertained to ACE D allele (odds ratio, OR, 2.08 [95% CI, 1.12-3.85], p = 0.02); factor XIII 34Leu allele (OR = 0.41 [95% CI, 0.18-0.95], p = 0.037] and MTHFR 677T variant (OR = 2.20 [95% CI 1.10-4.40], p = 0.026). We performed a meta-analysis on the associations between RVO and PAI-1 (n = 5), factor V Leiden (n = 21), MTHFR C677T (n = 19) and prothrombin G20210A (n = 21). We observed nominally significant associations only for PAI-1 (OR = 1.27 [95% CI, 1.02-1.60, p = 0.036]) (I(2) = 44.7%), and factor V Leiden (OR = 1.40 [95% CI, 1.07-1.84, p = 0.015]) (I(2) = 3.6%) using random effects model.

CONCLUSIONS

Our results suggest that there may be an association between increased risk for RVO and ACE I/D, MTHFR C677T, PAI-1 4G/5G and factor V Leiden polymorphisms, whereas the Val34Leu variant may exert a protective effect.

Hyperhomocysteinemia, as an independent risk factor for retinal venous occlusion in an Indian population

Total plasma homocysteine was analysed in 64 cases of retinal vein occlusion (RVO) of which 24 cases of central retinal vein occlusion (CRVO) and 40 cases of branch retinal vein occlusion (BRVO) and compared with 45 age and sex matched control. Homocysteine was significantly increased in RVO cases in respect to control (P < 0.001). Analysis also revealed that prevalence of rise of plasma homocysteine was more in cases of CRVO (OR = 13) than that of BRVO (OR = 5.03).

Diagnostic efficacy of total homocysteine and C-reactive protein for ocular ischemic syndrome

BACKGROUND

To assess diagnostic efficacy of plasma total homocysteine (tHcy) and C-reactive protein (CRP) levels for ocular ischemic syndrome (OIS).

METHODS

In all, 87 patients with retinal vein occlusion (RVO), 955 patients with a stenosis of internal carotid artery (ICA) <90% and 159 patients with a stenosis of ICA >90% were included between 2003 and 2009. A total of 43 patients with a stenosis ICA >90% were diagnosed as OIS. Fasting tHcy, CRP, lipid profiles, creatinine were measured, and diagnostic values of hyperhomocysteinemia or elevated CRP for OIS were evaluated.

RESULT

The mean plasma levels of tHcy (18.8 μmol/l) and CRP (1.1 mmol/l) were the highest in patients with OIS among the groups. The prevalences of hyperhomocysteinemia (72%) and elevated CRP (77%) were the highest in OIS among the groups. In patients with stenosis of ICA, the diagnostic sensitivity/specificity for OIS was 70/79% in hyperhomocysteinemia and 73/73% in elevated CRP. The diagnostic sensitivity and specificity for OIS were 53 and 86% in both hyperhomocysteinemia and elevated CRP. The lipid profiles and creatinine levels were similar among the groups.

CONCLUSION

Our results suggest that hyperhomocysteinemia and elevated CRP may be associated with the development of OIS. The measurements of tHcy and CRP in blood may help to assist the diagnosis of OIS in a stenosis of ICA.

Central retinal vein occlusion in a young Chinese population: risk factors and associated morbidity and mortality

PURPOSE

The purpose of this study was to assess the risk factors for central retinal vein occlusion and associated morbidity and mortality in a Chinese population.

METHODS

The participants included patients with central retinal vein occlusion 40 years old and younger. Predisposing factors, mortality, and systemic complications were examined in this group.

RESULTS

Unilateral (n = 19) and bilateral (n = 3) central retinal vein occlusions were identified in a total of 22 patients (25 eyes), with a mean follow-up time of 37 months. Hypercholesterolemia (65%), hypertriglyceridemia (64%), and hyperhomocysteinemia (42%) were all identified as risk factors. Three patients (14%) developed stroke and 1 (5%) developed transient ischemic attacks during follow-up. Renal failure and pulmonary hypertension resulted in the death of two patients. The mean initial and final visual acuities (+ or - standard deviation) were 20/400 (+ or - 20/250) and 20/500 (+ or - 20/320), respectively, and treatments did not result in vision improvement (P = 0.57). The poor visual prognosis was likely due to macular edema in 7 eyes (28%), optic atrophy in 4 eyes (16%), and secondary glaucoma in 3 eyes (12%).

CONCLUSION

Morbidity and mortality are high in young Chinese patients with central retinal vein occlusion who may have associated serious complications including stroke, blindness, and death. Central retinal vein occlusion may serve as an initial clinical presentation of serious systemic diseases.

Homocysteine, methylenetetrahydrofolate reductase C677T polymorphism, and risk of retinal vein occlusion: a meta-analysis

OBJECTIVE

To assess the role of plasma total homocysteine (tHcy) concentrations and homozygosity for the thermolabile variant of the methylenetetrahydrofolate reductase (MTHFR) C677T gene as risk factors for retinal vascular occlusive disease.

DESIGN

Retinal vein occlusion (RVO) is an important cause of vision loss. Early meta-analyses showed that tHcy was associated with an increased risk of RVO, but a significant number of new studies have been published.

PARTICIPANTS AND/OR CONTROLS

RVO patients and controls.

METHODS

Data sources included MEDLINE, Web of Science, and PubMed searches and searching reference lists of relevant articles and reviews. Reviewers searched the databases, selected the studies, and then extracted data. Results were pooled quantitatively using meta-analytic methods.

MAIN OUTCOME MEASURES

tHcy concentrations and MTHFR genotype.

RESULTS

There were 25 case-control studies for tHcy (1533 cases and 1708 controls) and 18 case-control studies for MTHFR (1082 cases and 4706 controls). The mean tHcy was on average 2.8 micromol/L (95% confidence interval [CI], 1.8-3.7) greater in the RVO cases compared with controls, but there was evidence of between-study heterogeneity (P<0.001, I(2) = 93%). There was funnel plot asymmetry suggesting publication bias. There was no evidence of association between homozygosity for the MTHFR C677T genotype and RVO (odds ratio [OR] 1.20; 95% CI, 0.84-1.71), but again marked heterogeneity (P = 0.004, I(2) = 53%) was observed.

CONCLUSIONS

There was some evidence that elevated tHcy was associated with RVO, but not homozygosity for the MTHFR C677T genotype. Both analyses should be interpreted cautiously because of marked heterogeneity between the study estimates and possible effect of publication bias on the tHcy findings.

FINANCIAL DISCLOSURE(S)

The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Comparative analysis of homocysteine concentrations in patients with retinal vein occlusion versus thrombotic and atherosclerotic disorders

The objectives of the present study were to determine the concentrations of plasma homocysteine in a large (n = 562) cohort of patients with retinal vein occlusion (RVO) and to compare them with the values observed in other vascular thrombotic and atherosclerotic conditions. Results were compared with those observed in patients with deep vein thrombosis (n = 1700), pulmonary embolism (n = 542), transient ischemic attack (n = 1301), cerebrovascular accident (n = 1299), myocardial infarction (n = 3087), as well as peripheral artery occlusive disease (n = 1946). No differences were found between the age-adjusted estimated marginal mean +/- SE for homocysteine concentrations in individuals with RVO and in those who had other atherosclerotic and atherothrombotic diseases The respective concentrations for RVO, deep vein thrombosis, pulmonary embolism, transient ischemic attack, cerebrovascular accident, myocardial infarction, and peripheral artery occlusive disease were 13.8 +/- 0.4, 14.7 +/- 0.3, 14.3 +/- 0.5, 14.2 +/- 0.3,14.6 +/- 0.3, 13.8 +/- 0.2, 14.4 +/- 0.2 pmol/l for men and 11.4 +/- 0.4, 10.7 +/- 0.2, 10.8 +/- 0.3, 10.8 +/- 0.2, 11.8 +/- 0.2, 11.2 +/- 0.2 pmol/l for women. In conclusion, the concentrations of homocysteine observed in patients with RVO are similar to those detected in other thrombotic and atherosclerotic vascular disorders. In view of the fact that this is a common disorder of the elderly, increased homocysteine concentrations often reported in patients with RVO could reflect the underlying atherothrombotic condition and might not necessarily be specifically related to the RVO per se. This information is relevant in researching the potential etiopathologic role, if any, of increased homocysteine concentrations in RVO.

Increased plasma asymmetric dimethylarginine (ADMA) levels in retinal venous occlusive disease

BACKGROUND

We investigated the levels of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine (ADMA), as well as homocysteine and cysteine thiols, in a cohort of subjects affected by retinal vein occlusion (RVO) disease.

METHODS

Capillary electrophoresis analysis was performed in both RVO subjects (n=54) and in a control group (n=32).

RESULTS

No differences were found between controls and patients; however, after categorisation for RVO type, central RVO (CRVO) patients showed higher levels of ADMA (0.710+/-0.139 micromol/L) than controls (0.635+/-0.117 micromol/L) and branch RVO patients (0.642+/-0.096 micromol/L). Moreover, cysteine plasma levels were also significantly higher in CRVO patients than in controls (265.8+/-46.9 vs. 226.7+/-51.9 micromol/L, p<0.01), while homocysteine plasma concentration was more or less identical in all groups.

CONCLUSIONS

We hypothesise that the elevated levels of cysteine in CRVO patients may post-translationally inhibit dimethylarginine dimethylaminohydrolase enzyme activity, as already described for homocysteine, thus contributing to the accumulation of ADMA in this patient group.

MTHFR C677T mutation in central retinal vein occlusion: a case-control study in Chinese population

Our previous study found that hyperhomocysteinemia was strongly associated with central retinal vein occlusion (CRVO) in the Chinese population. The aim of this study is to determine whether MTHFR C677T mutation is an independent risk factor for CRVO in the Chinese population. A matched case-control study was conducted between July 2004 and May 2005. The study cohort consisted of 64 individuals that had been diagnosed with CRVO and 64 healthy controls (matched for age, gender, hypertension, smoking, and drinking habits). None of the cases or controls had a history of diabetes, glaucoma, medication or any other vascular events that might influence plasma homocysteine levels. A cross-sectional analysis among the 64 cases was performed to compare the prevalence of MTHFR C677T mutation among subjects with and without ischemia and subjects aged above 45 and below 45 years. MTHFR C677T mutation was determined by the template-directed dye-terminator incorporation with fluorescence polarization (TDI-FP) method. The result showed that the prevalence of the MTHFR 677 TT genotype did not significantly differ between patients and controls. However, 10 (34.5%) MTHFR C677 TT genotype was found in the ischemic group but only 4 (14.3%) in the nonischemic group (p=0.026). And we found that 6 MTHFR C677 TT genotype patients who have hyperhomocysteinemia in the ischemic group but only 2 in the nonischemic group (p=0.016). It suggests that MTHFR C677T mutation is associated with hyperhomocysteinemia in the ischemic CRVO in the Chinese population. It may contribute to hyperhomocysteinemia and associate with the development of CRVO.

Hyperhomocysteinemia and central retinal vein occlusion in Iranian population

PURPOSE

To evaluate total plasma homocysteine level during the acute phase of central retinal vein occlusion (CRVO) in the Iranian population and determine whether hyperhomocysteinemia is also a risk factor for CRVO.

METHODS

Fifty-four patients with recently diagnosed CRVO were studied. Their fasting total plasma homocysteine level was compared with a matched control group of 51 patients evaluated in the same clinic for a non-retinal disease diagnosis.

RESULTS

The mean total plasma homocysteine level was 14.76+/-7.67 micromol/l in cases, and 11.42+/-3.74 micromol/l in control subjects. It showed a significant difference (P=0.005) in mean plasma homocysteine level between cases and control group. Odds ratio of CRVO for individuals with hyperhomocysteinemia was 2.88 (95% CI=1.08-7.71 and P=0.03). The overall multivariable-adjusted odds of CRVO in participants with plasma homocysteine level above 15 micromol/l was 4.71 (95% CI=1.46-15.19 and P=0.009) Hyperhomocysteinemia was not statistically different in each age group (<60 years: 27%, 61-70 years: 33.3%, 71-80 years: 31.6%, >81 years: 33.3%, Chi-square test, P=0.98).

CONCLUSION

Elevated total plasma homocysteine level is an independent risk factor for CRVO in Iranian population. In addition to an evaluation of all conventional cardiovascular risk factors, measurement of total homocysteine for evidence of hyperhomocysteinemia may be important in the initial investigation and management of patients with CRVO.

Role of hyperhomocystinemia in retinal vascular occlusive disease

Elevated plasma homocysteine (Hcy) level is considered a risk factor for vascular diseases. In recent years, many scientific reports have suggested that hyperhomocystinemia may be associated with an increased risk of retinal vascular occlusive disease (RVOD). The prevalence of elevation of homocysteine in patients with a recent retinal vascular occlusion was compared to a health control group in this study. Forty-nine consecutive patients (22 M; 27 F) (age 26-85 years, mean 69) with diagnosis of retinal vascular occlusion were compared with 71 healthy controls. These patients underwent laboratory evaluation for plasma fasting total homocysteine, activated protein C resistance, protein C, protein S, antithrombin III, and antiphospholipid and anticardiolipin antibodies. The G20210 prothrombin gene mutation (FII G20210A) and Factor V Leiden mutation (FVL) were evaluated. None of these enrolled subjects had other prothrombic risk factors. The health control group consisted of healthy subjects from the general population, with no history or clinical evidence of retinal vascular disease, recruited during the same 2-year period. High fasting homocystinemia (higher than 15 mumol/L) was detected in 24/49 subjects (48.9%) (P < .0005). There was a high prevalence of hyperhomocystinemia: these data suggest an association between RVOD and high fasting homocystinemia. Elevated homocysteine may be an independent risk factor, and its assessment may be important in the investigation, management, and follow-up of patients with RVOD. Further controlled studies are necessary to clarify the exact role of hyperhomocystinemia in RVOD and to evaluate the appropriate therapeutic approach.

MODERATE HYPERHOMOCYSTEINEMIA AND EARLY-ONSET CENTRAL RETINAL VEIN OCCLUSION

PURPOSE

To evaluate the prevalence of moderate fasting hyperhomocysteinemia (HHcy) and postmethionine load (PML) HHcy among patients with early-onset central retinal vein occlusion (CRVO).

METHODS

The prevalence of fasting HHcy and that of PML HHcy were evaluated in a consecutive series of 58 patients with CRVO who were younger than 56 years of age (mean age, 40.3 years) and in 103 controls (mean age, 39.6 years). Plasma folate, vitamin B12, and pyridoxal-5'-phosphate (PLP) levels were measured in 42 patients and 67 controls.

RESULTS

Mantel-Haenszel odds ratios for CRVO patients were 3.00 (95% confidence interval [CI], 0.83-10.8) for fasting HHcy, 3.50 (95% CI, 1.07-11.4) for PML HHcy, and 3.00 (1.18-7.6) for fasting HHcy and PML HHcy in subjects with normal fasting total homocysteine (tHcy) levels. Moderate HHcy was associated with reduced plasma levels of folate and PLP (P < or = 0.04). There was no significant dependence of fasting and PML tHcy levels on any traditional risk factor evaluated.

CONCLUSIONS

Moderate HHcy is an independent risk factor for early-onset CRVO.

Homocysteine, MTHFR C677T gene polymorphism, folic acid and vitamin B 12 in patients with retinal vein occlusion

Background

Many available data have suggested that hyperhomocysteinaemia, an established independent risk factor for thrombosis (arterial and venous), may be associated with an increased risk of retinal vein occlusion (RVO).

Aim of the study

To evaluate homocysteine metabolism in consecutive caucasian patients affected by RVO from Northern Italy.

Patients and Methods

69 consecutive patients from Northern Italy (mean age 64.1 ± 14.6 yy) with recent RVO, were tested for plasma levels of homocysteine (tHcy: fasting and after loading with methionine), cyanocobalamine and folic acid levels (CMIA-Abbot) and looking for MTHFR C677T mutation (Light Cycler-Roche) and compared to 50 volunteers, enrolled as a control group.

Results

Fasting levels of tHcy were significantly higher in patients than in controls: mean value 14.7 ± 7.7 vs 10.2 ± 8 nmol/ml. Post load levels were also significantly higher: mean value 42.7 ± 23.7 vs 30.4 ± 13.3 nmol/ml; Total homocysteine increase was also evaluated (i.e. Δ-tHcy) after methionine load and was also significantly higher in patients compared to control subjects: mean Δ-tHcy 27.8 ± 21.5 vs 21.0 ± 16 nmol/ml (normal value < 25 nmol/ml). Furthermore, patients affected by RVO show low folic acid and/or vitamin B12 levels, although differences with control group did not reach statistical significance. Heterozygous and homozygous MTHFR mutation were respectively in study group 46% and 29% vs control group 56% and 4%.

Conclusion

our data confirm that hyperhomocysteinaemia is a risk factor for RVO, and also that TT genotype of MTHFR C677T is more frequently associated with RVO: if the mutation per se is a risk factor for RVO remains an open question to be confirmed because another study from US did not reveal this aspect.

Hyperomocysteinemia is modifiable risk factor for thrombotic diseases. Therefore, a screening for tHcy plasma levels in patients with recent retinal vein occlusion could allow to identify patients who might benefit from supplementation with vitamins and normalization of homocysteine levels, in fasting and after methionine load.