Association of thromboxane A2 receptor gene polymorphism with the phenotype of acetyl salicylic acid-intolerant asthma

Background and objective The thromboxane A2 receptor (TBXA2R) is a receptor for a potent bronchoconstrictor, TBXA2 which is known to be related to bronchial asthma and myocardial infarction. TBXA2R antagonist and TBX synthase inhibitors have been found to be effective in the management of asthmatic patients. This study was aimed to evaluate whether genetic variants of TBXA2R may be related with development of acetyl salicylic acid (ASA)-intolerant asthma (AIA). Methods TBXA2R gene polymorphisms (TBXA2R+795T > C, TBXA2R+924T > C) were determined using a single-base extension method in 93 AIA patients compared with 172 patients with ASA-tolerant asthma (ATA) and 118 normal controls (NCs) recruited from the Korean population. HLA DPB1(*)0301 genotype was performed using a direct sequencing method. Results The rare C allele frequency of TBXA2R+795T > C was significantly higher in AIA than in ATA (P=0.03) and the TBXA2R+795T > C polymorphism was also associated with extent of percent fall in forced expiratory volume in 1 s (FEV1) after the inhalation of lysine-acetyl salicylic acid in AIA patients (P=0.009); AIA patients homozygous for the +795 C allele had a greater percent fall of FEV1 compared with individuals with TBXA2R+795 CT or TT genotypes. The frequency of patients carrying both the TBXA2R+795T > C rare allele and HLA DPB1(*)0301 was significantly higher in AIA patients (29.4%) than in ATA patients (7.3%) (P=0.008, odds ratio=5.3). Conclusion These results suggest that the polymorphism of TBXA2R+795T > C may increase bronchoconstrictive response to ASA, which could contribute to the development of the AIA phenotype.