Abstract 2130: A Variant in Intron 1 of the Platelet Endothelial Aggregation Receptor-1 (PEAR1) Gene is Strongly Associated With Increased Platelet Aggregability
We previously reported a variant in the distal promoter region of the PEAR1 gene that is associated with increased platelet aggregability. We now identify a much stronger signal from a single nucleotide polymorphism (SNP) in intron 1 of the gene that is replicable and may represent the functional variant. We measured maximal platelet aggregation in PRP to various doses of collagen (col), epinephrine (epi), and ADP at baseline and after 2 weeks of aspirin (ASA), 81 mg/day, in 2076 apparently healthy subjects enrolled in GeneSTAR (1241 white, 835 African Americans (AAs)). We genotyped 20 SNPs in PEAR1 (Illumina platform). Genotype/phenotype family-based associations were determined separately by race using ASSOC, after adjustments for age, sex, and coronary risk factors. There were several significant SNP associations with both baseline and post ASA phenotypes, but the strongest was for rs12041331 in intron 1, particularly for post ASA platelet aggregation (whites: p=4.1×10 −5 for col, 3.7×10 −8 for epi, 1.3×10 −3 for ADP; AAs: p=2.4×10 −13 for col, 5.6×10 −26 for epi, 4.5×10 −8 for ADP). The associations at rs12041331 were replicated for baseline platelet aggregation phenotypes in the Framingham Heart Study (FHS) (white subjects, n=2350) (p=2.1×10 −6 for epi, 3.6×10 −6 for ADP). rs12041331(MAF 9% whites, 40% AAs) was associated with increased platelet aggregation with all agonists and explained up to 14.5% of the variance in aggregation. We sequenced the entire PEAR1 gene in 104 subjects at the extremes of aggregation to look for functional variants; no structural changes were found, but rs12041331 was again most strongly associated with aggregation differences. Western blotting of platelet lysates showed that homozygotes for the variant at rs12041331 (GG) had significantly higher PEAR1 protein expression than homozygotes for the major allele (AA, p=0.007). rs12041331 is located at a predicted leucine zipper factor binding site (AliBaba2.1), suggesting a potential mechanism for PEAR1 regulation by the variant. In conclusion, rs12041331 in intron 1 of PEAR1 is strongly associated with increased platelet aggregation to multiple agonists, is replicated in FHS, is associated with increased PEAR1 protein expression, and may represent the functional variant.