Associations and LD structure for ITPR1. (A) Association of the 61 SNPs in the ITPR1 locus on chromosome 3p26.1 for each of the 4 functional platelet responses (reading from the top; PA, PC, FA, and FC). Arrow indicates the SNP with the highest association in the PA response. LD structure is based on HapMap data (as described for Figure 4), and chromosomal position in Mb based on NCBI build 36 coordinates, showing Ensembl (version 49) gene structure. (B) Calcium flux (shown as area under the curve) in response to 3 concentrations of ADP (10⁻⁷, 10⁻⁶, 10⁻⁵ M) and 5 μg/mL CRP-XL. Data are shown as the mean ± for subjects homozygous for the major allele of rs17786144 (CC) (■; n = 10), heterozygous (CT) (, n = 7), or homozygous for the minor allele (TT) (□, n = 4). (C) Calcium flux (shown as time to peak calcium) in response to 3 concentrations of ADP (10⁻⁷, 10⁻⁶, 10⁻⁵ M) and 5 μg/mL CRP-XL. Data are shown as the mean ± SD for subjects homozygous for the major allele or rs17786144 (CC) ■; n = 10), heterozygous (CT) (; n = 7), or homozygous for the minor allele (TT) (□; n = 4). (D) Example of flow cytometric histogram of expression of ITPR1 protein in platelets from subjects homozygous for the major allele of rs1786144 (solid line), heterozygous (dotted line), or homozygous for the minor allele (dashed line), illustrating the lack of effect of genotype on the level of expression. (E) Expression of ITPR1 protein, measured by flow cytometry, in platelets from 10 subjects homozygous for the major allele of rs1786144 (CC), 7 heterozygotes (CT), and 4 subjects homozygous for the minor allele (TT). (ns for all).