Key Points• This paper describes the effect of fibrinogen g9 on clot structure in plasma (previously shown in purified systems).• This paper also describes the respective roles of total fibrinogen, fibrinogen g9 concentration, and ratio on clot structure and lysis rates.Fibrinogen g9 is known to influence fibrin clot structure in purified experimental models, but little is known regarding its influence on clot structure in plasma. Furthermore, the environmental and biological factors that affect its concentration are poorly described. We analyzed fibrinogen g9, total fibrinogen concentration, and fibrin clot structure in 2010 apparently healthy black South Africans and related them to traditional cardiovascular disease (CVD) risk factors. Fibrinogen g9 generally increased with increasing fibrinogen concentration, but a decreased g9/total fibrinogen ratio was found at the highest total fibrinogen concentrations. Clot maximum absorbance increased with total fibrinogen and fibrinogen g9, but decreased with g'/total fibrinogen ratio. Clot lysis time showed a stronger relationship with fibrinogen g9 than with total fibrinogen, whereby increased fibrinogen g9 delayed clot lysis. CVD risk factors (excluding fibrinogen) explained 20% and 3%, respectively, of the variance in fibrinogen g9 and the g9/total fibrinogen ratio, with Creactive protein making the biggest contribution. More than 50% of the variance in fibrinogen g9 and g9/total fibrinogen ratio is explained by factors other than total fibrinogen or other traditional CVD risk factors. Our data show that fibrinogen g9 modulates plasma clot structure and fibrinolysis and is also influenced by factors other than fibrinogen. (Blood. 2013;121(16):3254-3260)

SummaryInter-ethnic variation in fibrinogen levels is hypothesized to be the result of differences in genetic background. No information is available regarding the contribution of genetics to fibrinogen c 0 in Africans. Only limited information is available regarding the interaction between genotypes and total and c 0 fibrinogen concentration in determining fibrin clot properties.Our aim was to investigate the effect of polymorphisms in the fibrinogen and Factor XIII genes on total and c 0 fibrinogen and clot properties (turbidimetry) in 2010 black Africans as well as to determine their interactions. Significant associations were observed between rs1049636 (FGG gene), with total fibrinogen levels and between rs2070011 (FGA promoter area) and fibrinogen c 0 levels. Significant associations were observed between single nucleotide polymorphisms (SNPs) in the FGA (rs2070011), FGB (rs1800787) and FGG (rs1049636) genes and fibre size. Significant interactions were found between total and/or c 0 fibrinogen levels and SNPs in the FGA (rs2070011), FGB (rs2227385, rs1800787, rs1800788, rs4220) and F13A1 genes (rs5985) in determining clot properties. The different SNPs influenced the relationships between total and c 0 fibrinogen levels with clot properties in opposing directions. Genetic influences may be ethnic-specific and should not only focus on fibrinogen concentration, but also on functionality in determining its role in CVD.

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The role of ethanol metabolism in possible haemostatic cardioprotective effects has not yet been determined. To this end, we investigated the effect of a moderate dose of ethanol (35 g) and its metabolism, on haemostatic variables over 14 hours (h). Eighteen Caucasian males participated in a placebo-controlled, randomised, cross-over study. Blood was collected prior to alcohol consumption, and at 10 time points for 14 h. Blood ethanol peaked at 1 h and was cleared after 8 h following ethanol consumption, significantly increasing plasma acetate (p=0.0028). Ethanol did not influence the coagulation factors significantly. PAI-1act increased (p<0.0001) and tPAact (p=0.047) decreased following alcohol consumption, reaching maximum (0.69 to 22.2 IU/ml) and minimum (0.88 to 0.33 IU/ml) levels at 5 h, respectively. Significantly increased plasma clot lysis times (46.8 to 67.6 minutes) and reduced global fibrinolytic capacity of whole blood, measured as D-dimer production during incubation of blood clots (2.26 to 0.29 μg/ml), were found at 5 h. Except for PAI-1act (borderline significance; p=0.05), there was no significant difference in the fibrinolytic markers between the two groups the following morning. Moderate ethanol consumption resulted in a significant temporary fibrinolysis inhibition. Any protective effects of moderate ethanol consumption on cardiovascular disease do not appear to be due to improvement in fibrinolytic potential within the first 14 h following consumption. The use of global fibrinolytic assays is recommended for determining the true effect of ethanol on fibrinolysis.