Thromboxane A2 receptor gene polymorphism is associated with the serum concentration of cat-specific immunoglobulin E as well as the development and severity of asthma in Chinese children.

Thromboxane A2 and its receptor (TBXA2R) are involved in the constriction of vascular and respiratory smooth muscles. The T924C polymorphism in the TBXA2R gene was recently found to be associated with asthma in Japanese adults but not in children. Its relationship with atopy or asthma severity in children has not been defined. To investigate this further, we first assessed the severity of asthma in Chinese children using a standardized questionnaire modified from the Disease Severity Score and spirometric evaluation. Then, peripheral blood was analyzed for serum total and aeroallergen-specific immunoglobulin E (IgE) levels, and TBXA2R T924C genotypes were determined by restriction fragment length polymorphism (RFLP) analysis. One-hundred and fifty three asthmatic patients and 57 control children were recruited, of respective mean ages 9.9 and 11.0 years (p = 0.07). The mean logarithmic serum total IgE concentration was 2.57 and 2.09, respectively, for the asthmatic group and control group (p < 0.0001). Atopy was detected in 132 (86%) asthmatics and 33 (58%) controls. A significant association was observed between T924C and the diagnosis of atopic asthma (p = 0.044; odds ratio: 1.84). In addition, those asthmatics homozygous for the mutant allele in T924C had a lower forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) (p = 0.032 and 0.002, respectively). Among our asthmatic patients, the TBXA2R T924C polymorphism correlated with the concentration of cat-specific IgE in serum (p = 0.046). Nonetheless, this gene marker did not show an association with the serum total IgE concentration or any clinical indicator of asthma severity. In conclusion, our results suggest that the T924C marker in the TBXA2R gene is associated, in Chinese children, with an increased susceptibility of developing atopic asthma. This marker is also associated with the extent of allergic sensitization to cat, as well as with reduced FEV1 and FVC values.