Association analysis of TAS2R31 single- nucleotide variants with asthma, smoking, clinical and functional features of the disease

   Introduction. Bitter taste receptors TAS2R31 can be expressed on respiratory epithelium, leukocytes, bronchial smooth muscles, and are capable of mediating relaxation of smooth muscle cells. Nevertheless, data on the relationship of TAS2R31 single nucleotide variants (SNVs) with asthma, as well as with various phenotypic features of the disease, are currently lacking.

   Aim. To analyze the spectrum of TAS2R31 SNVs in patients with asthma and practically healthy volunteers and to evaluate their possible relationship with the presence of the disease, smoking, lung function parameters and the level of asthma control.

   Materials and methods. The study included 119 patients with persistent asthma (main group, 40 % males, 48.5 ± 1.51 years) and 72 practically healthy volunteers (control group, 58% males, 38.2 ± 1.15 years). Detection and genotyping of TAS2R31 SNVs were performed within the amplified 839 bp gene fragment by Sanger sequencing. Lung function was assessed by standard spirometry, and asthma control was determined using the ACT questionnaire.

   Results. In total, five SNVs were identified in the combined sample of patients and controls: rs10845295 (p.Arg35Trp), rs12370363 (p.Ala141=), rs10743938 (p.Leu162Met), rs10845293 (p.Ala227Val), and rs10772423 (p.Val240Ile). The association with asthma was tested for rs12370363 and rs10743938, whereas associations with smoking, asthma control and lung function were analyzed for rs10845295, rs12370363 and rs10743938. SNV rs10743938 was significantly associated with the presence of asthma (OR 1.95 95% CI (1.11-3.43), p = 0.02 in the log-additive model after adjusting for gender, age, and smoking status). The same SNV was associated with smoking among asthma patients (OR 1.9 95 % CI (1.02-3.75), p = 0.04 in the log-additive model after adjusting for gender and age). No significant associations were found between the studied SNVs with lung function parameters or asthma control.

   Conclusion. In the examined samples, the spectrum of common TAS2R31 SNVs was relatively limited and only partially overlapped with the extensive list of common variants reported in public genetic databases. The present study revealed an association of the rs10743938 A allele with asthma and smoking among asthma patients, suggesting a potential role for TAS2R31 variations in the development of genetic predisposition to the disease and smoking in the presence of asthma.

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