Association of HTR2A-1438G/A Genetic Polymorphism With Smoking and Chronic Obstructive Pulmonary Disease

Cigarette smoking is a major risk factor in the development of chronic obstructive pulmonary disease (COPD). Serotonin levels have been associated with COPD and smoking has been as a significant modulator. Elevated levels of serotonin are responsible for bronchoconstriction and pulmonary vasoconstriction and also nicotine dependence, thus serotonin response could be affected by genetic polymorphisms in transporters and receptors of serotonin.

The aim of the current study was to analyze the effect of SLC6A4 (5HTT_LPR) (rs25531) and HTR2A-1438G/A (rs6311) genetic polymorphisms on the relation between smoking habits and COPD.

The association between SLC6A4 (5HTT_LPR) (rs25531), HTR2A-1438G/A (rs6311), smoking degree and COPD was analyzed in a total of 77 COPD patients (active smokers) and 90 control subjects (active healthy smokers). The DNA was extracted of peripheral leukocytes samples and genotyping was performed using an allele specific polymerase chain reaction.

The distribution of SLC6A4 genotypes did not vary between healthy smokers and COPD patients (P=0.758). On the other hand, the A allele of HTR2A (rs6311) was significantly associated with COPD incidence in the trend model (P=0.02; 1.80 [1.04-3.11]). Among all smokers, this allele was also associated with the number of pack years smoked (P=0.02) and also, we observed a marginal association with FEV1/FVC values (P=0.06).

Our results point a possible role of the A allele of HTR2A (rs6311) in COPD pathogenesis, suggesting that this effect depends partly on tobacco consumption due to a gene-by-environment interaction.