Thrombophilic mutations as risk factor for retinal vein occlusion: a case-control study.

BACKGROUND: Retinal vein occlusion (RVO) is the second most common retinal vein disease and an important cause of blindness and visual morbidity. Many conditions are associated with RVO but the real role of the thrombophilic mutations is still unclear. AIM: To evaluate the potential role of thrombophilic mutations in RVO. METHODS: We have evaluated 113 patients with RVO and compared with 104 volunteer controls. The controls were all healthy blood donors without previous venous thromboembolism episode or arterial thromboembolism episode. All patients were tested for 5 gene variants (here all named as mutations): factor V (FV) Leiden (G1691A), factor II (FII; G20210A), 5,1-methylenetetra-hydrofolate reductase (MTHFR; C677T), plasminogen activator inhibitor 1 (PAI-1; 4G/5G), and angiotensin-converting enzyme (ACE; Del/Ins). Statistical analysis were performed by the 2-tailed chi-square test. RESULTS: Statistical test showed that TT homozygous patients of the MTHFR C677T mutation (P = .017) and heterozygous GA patients of the FII G20210A mutation (P = .018) were significantly higher than that in controls. For FV Leiden, even if the values were higher in patients than in controls, P value was not statistically significant. Conversely, for the ACE (Ins/Del) and PAI-1 (4G/5G) mutations, no difference was observed among genotypes of patients with RVO and control participants. CONCLUSIONS: In our study, the FII G20210A and the MTHFR C677T mutations resulted significantly higher in patients than in controls; in contrast, thrombophilic mutation of FV, ACE, and PAI-1 genes was not statistically correlated with RVO. In spite of having found an association between some thrombophilic mutations and RVO, more studies with a major number of patients are necessary to determine the final role of these gene variants.

Retinal vein occlusion: evaluation of "classic" and "emerging" risk factors and treatment.

Retinal vein occlusion (RVO) is the second most common retinal vein disease and an important cause of blindness and visual morbidity. Systemic risk factors are commonly associated with RVO, while unclear it is the role of the thrombophilic and coagulation disorders. To evaluate "classic" and "emerging" risk factors, and to establish a good treatment for RVO. Fifty patients, 31 males and 19 females, with RVO were selected for our study. RVO patients were divided into two groups: those with central retinal vein occlusion (CRVO) and those with branch retinal vein occlusion (BRVO). All patients were subjected to an anamnestic investigation and were tested for thrombophilia, coagulation disorders and hyperlipidemia. Treatment and prophylaxis were evaluated. We have named "classic" the systemic risk factors associated with RVO and "emerging" those risk factors, haemostasis related, not clearly associated with RVO. RVO occurs more commonly in patients aged over 50. "Emerging" risk factors were more frequent in CRVO, "classic" in BRVO. Hyperhomocysteinemia is the most common "emerging" risk factor related to RVO. 71.4% of tested patients had hypercholesterolemia. Treatment with LMWH would appear to be safe and effective, but the small number of patients considered not allow us a definitive evaluation of its efficacy. Although our study has shown the correlation between RVO and the "emerging" risk factors, more studies are necessary to better know the real role of thrombophilic and coagulation disorders in this disease and to determine a specific protocol for the treatment and prophylaxis of RVO.

WITHDRAWN: Retinal vein occlusion: Risk factors evaluation, treatment and prophylaxis.

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Red blood cell senescence and neocytolysis in humans after high altitude acclimatization.

A selective lysis of relatively young erythrocytes (neocytolysis), together with a decrease of erythropoietin (EPO) production, has been described in polycythemic, high altitude acclimatized climbers, after descent to sea level, and in astronauts, soon after exposure to weightlessness (Alfrey CP, Rice L, Udden MM, Driscoll TB. Neocytolysis may represent the physiological down-regulation of red-cell mass. Lancet 349 (1997) 1389-90). To study neocytolysis, we analysed blood samples drawn from 4 mountain climbers at sea level before and after 53 days of high altitude acclimatization (> or = 4500 m). After a 6-day descent to sea level, erythropoietin (EPO) plasma levels were lower than before high altitude acclimatization (mean values: 2.5+/-3.3 versus 10+/-4.5 mIU/ml, p < 0.05). Red blood cell (RBC) populations were separated into low, middle and high density subsets, which, by physical and phenotypical criteria, were characterized as young, middle-aged and old. RBC membrane molecules CD55 and CD59 along with phosphatydylserine and CD47 were measured. The former are partially lost during RBC aging. The latter are involved in the triggering or inhibition of RBC phagocytosis by macrophages. Immunofluorescence and flow cytometry were done on each density subset. Young and middle-aged RBCs largely disappeared after descent from high altitude (from 4.50% (+/-3.10) and 66% (+/-6.90) to 0.19% (+/-0.07) and 1.90% (+/-0.50), respectively). Simultaneously, there was a dramatic increase of high density RBCs (from 29.50% (+/-7) to 97.90% (+/-2.00)). Furthermore, the remaining young and middle-aged RBCs had acquired a senescent-like phenotype, which may account for their increased susceptibility to phagocytosis.