Selectin haplotypes and the risk of venous thrombosis: influence of linkage disequilibrium with the factor V Leiden mutation

Summary.  Background:  Selectins (E-, L- and P-selectin) and their most important counter-receptor P-selectin glycoprotein ligand (SELPLG) facilitate the interaction of platelets, leukocytes and endothelial cells at inflammatory sites. Selectin polymorphisms/haplotypes have been associated with cardiovascular disease. Objectives:  We investigated the association between haplotypes (H) of these four genes and deep venous thrombosis (DVT) risk. We additionally explored the effect of linkage disequilibrium (LD) with the nearby Factor V Leiden mutation (FVL). Furthermore, interactions between SELPLG polymorphisms and selectin polymorphisms were investigated. Patients/methods:  Leiden Thrombophilia Study (LETS) subjects were genotyped for 24 polymorphisms by Taq Man or PCR–RFLP, detecting all common haplotypes in four blocks. P-selectin was analyzed in two blocks, upstream (SELPup) and downstream (SELPdown) of the recombination hotspot. Results:  In E- and L-selectin, none of the haplotypes was associated with DVT risk. In SELPup, H2-carriers had a 1.3-fold increased risk (95% CI, 1.0–1.7), whereas H4-carriers had a 1.4-fold decreased risk (95% CI, 0.5–1.0). In SELPdown, H2-carriers had a 1.3-fold increased risk (95% CI, 1.0–1.7). Because of LD with FVL, we subsequently excluded all FVL-carriers and all risks disappeared. Mutual adjustment within a logistic regression model resulted in disappearance of the risks for the SELP haplotypes, whereas FVL risk remained. Conclusions:  After adjustment for LD with FVL, none of the selectin haplotypes was associated with DVT risk, showing that the increased risks of the selectin haplotypes were a reflection of the effect of FVL on thrombosis risk.