Lack of association between ADRB2 (Gln27Glu) variant with susceptibility, severity and salbutamol response in South Indian asthmatics

ADRB2 gene polymorphisms have been widely studied for their role in influencing asthma pathophysiology. Of particular note, the Gln27Glu (+ 79 C > G, rs1042714) polymorphism, which alters the extracellular domain at the N-terminus of β2AR, leads to the expression of an immature protein. While this polymorphism has been studied in various ethnic groups, its relevance in South Indian asthmatics remains unexplored. The present study, hence, evaluates its association with asthma susceptibility, lung function, disease severity, and response to β2 agonists (salbutamol) in the South Indian cohort. A total of 398 clinically diagnosed asthma patients and 456 healthy controls were recruited. Lung function was assessed using spirometry with age- and race-adjusted values, and severity was classified according to GINA guidelines. Bronchodilator response was assessed by spirometry before and 15 min after salbutamol (200 µg) administration, with a response threshold measured at FEV1 reversibility of ≥ 12%. Genotyping was conducted via allele-specific PCR on blood-derived genomic DNA. Statistical methods were applied to test for the significance of the results. In the present study, there was a lack of significant association between Gln27Glu polymorphism with disease susceptibility, lung function, severity, and bronchodilator response. Additionally, the polymorphism showed no association with response phenotypes across severity subsets. In conclusion, Gln27Glu does not appear to be a crucial ADRB2 polymorphism in asthma susceptibility, nor does it hold clinical significance in modulating pathological conditions, suggesting its limited relevance in South Indian asthmatics.