Summary
Background. A high level of red blood cell (RBC) aggregation has been consistently found in
patients with coronary artery disease (CAD) in case-control studies. Plasma fibrinogen
has been shown to promote RBC aggregability. The purpose of this study was to investigate
the influence of the genetic variability of the β-fibrinogen gene on RBC aggregation
in patients with CAD. Methods and Results. The genotype of the β-fibrinogen gene locus was determined by polymerase chain reaction
using the restriction enzyme HaeIII for a G to A substitution at position -455 upstream from the transcriptional start
site in 135 French Canadians with premature CAD (age: 51 ± 7 years). Indices measuring
the RBC aggregation kinetics (S10) and shear resistance of the aggregates (γS) were obtained by laser reflectometry.
Patients were separated into groups by using the medians of S10 and γS. Using χ2 analyses, the distribution of the -455GG, -455GA, and -455AA genotypes in the groups
with high levels of S10 (0.43, 0.49, and 0.08) and γS (0.45, 0.49, and 0.06) were found to be significantly
distinct from those in the groups with low levels of S10 (0.67, 0.27, and 0.06; p <0.05) and γS (0.70, 0.23, and 0.07; p <0.01). High levels
of RBC aggregation were closely associated with the rare -455A allele. Multivariate
linear regression analyses showed that S10 was positively correlated with the linear combination of the fibrinogen concentration,
age, and the -455G/A genotype (adjusted r = 0.63, p <0.0001). Fibrinogen and age were positive determinants, and HDL-cholesterol was
a negative predictor of γS (adjusted r = 0.51, p <0.0001). Conclusion. These findings support the hypothesis that RBC hyperaggregation in premature CAD
may be associated with the β-fibrinogen -455G/A polymorphism. This association may
be explained by a change in the concentration and/or the functional properties of
the fibrinogen protein.
Keywords
Erythrocyte aggregation - β-fibrinogen gene - genetics - coronary artery disease -
fibrinogen - lipids - lipoproteins