Supplementary Material for: Possible Association of <i>SLC22A2</i> Polymorphisms with Aspirin-Intolerant Asthma

<i>Background:</i> Aspirin-intolerant asthma (AIA) is a clinical syndrome characterized by acute bronchoconstriction following the ingestion of aspirin. Solute carrier family 22, member 2 (SLC22A2), also known as organic cation transporter 2 (OCT2), is predominantly expressed in the luminal membrane of airway epithelial cells and has been shown to mediate the transport of prostaglandins on the cyclooxygenase pathway which is regulated by aspirin blockage. Recently, SLC22A2-mediated uptake inhibition by several nonsteroidal anti-inflammatory drugs and decreased SLC22A2 transport activity by its genetic variants have been elucidated in asthma. <i>Methods:</i> To investigate the associations between AIA and genetic polymorphisms of the <i>SLC22A2</i> gene, 18 variants were genotyped in 163 AIA subjects and 429 aspirin-tolerant asthma (ATA) controls. Logistic analyses were used to evaluate p values for the associations of <i>SLC22A2</i> polymorphisms with AIA. <i>Results:</i> One common polymorphism in intron 5, i.e. <i>rs316021</i>, was significantly associated with susceptibility to AIA (p<i> = </i>0.004, <i>P</i><sup>corr</sup> <i>= </i>0.05, OR = 0.60, 95% CI = 0.43–0.85 in a codominant model). The minor allele frequency of <i>rs316021</i> in the AIA group was significantly lower than that in the ATA controls. In addition, a polymorphism in intron 4 <i>(rs3912161)</i> and a haplotype <i>(SLC22A2-ht3)</i> showed significantly stronger association signals with the FEV<sub>1</sub> fall rate induced by aspirin provocation in AIA subjects compared with ATA controls (p <i>= </i>0.004, <i>P</i><sup>corr</sup><i> = </i>0.05). <i>Conclusion:</i> Our findings suggest that <i>SLC22A2</i> could be a susceptibility gene for aspirin intolerance in asthmatics.