Objective: To characterize the genetic and clinical correlates of soluble P-selectin, and the relationship of P-selectin to atherosclerotic risk, in young European-American (EA) and African-American (AA) adults.
Methods and results: We assessed the interrelationships between 25 common SELP polymorphisms, soluble P-selectin, and atherosclerotic risk in 1222 EA and 1072 AA from the longitudinal population-based CARDIA study. Male sex, smoking, blood pressure, and metabolic status were strong cross-sectional correlates of soluble P-selectin among CARDIA subjects aged 33 to 45 years, explaining 13% of the variance. Among EAs, higher soluble P-selectin predicted carotid intima-media thickness (IMT) measured 5 years later, even after accounting for traditional risk factors. Common SELP nucleotide sequence variants explained 11% and 5% of the interindividual variation in soluble P-selectin levels in EAs and AAs, respectively. Four distinct variants contributed to P-selectin phenotype in EAs, including a polymorphism of the 5' SELP haplotype block associated with carotid IMT. Half of the phenotypic variation attributable to SELP in EAs could be explained by the Thr715Pro polymorphism, whereas Val599Leu was more strongly associated with soluble P-selectin among AAs.
Conclusions: Common SELP polymorphisms were associated with soluble P-selectin and carotid IMT in young adults, but the patterns of association differed between EAs and AAs. These results support the role of P-selectin in the preclinical stages of atherosclerosis.