HTR4 and chronic obstructive pulmonary disease: Several loci linked to lung function in the general population, such as the rs10516526, rs11168048 and rs11155242 SNPs (GSTCD on 4q24, HTR4 on 5q33, and GPR126 on 6q24, respectively) [22], [23] do not appear to be related to COPD in this study.