The Th17 cells contribute to the pathogenesis of COPD mainly by producing IL-17A, which facilitates neutrophilic inflammation in the small airways and induces lymphoid neogenesis formation by B cells attracting the chemokine C-X-C motif ligand (CXCL) 12 during the progression of COPD [10,11]. The gene discussed is IL17A; the disease is chronic obstructive pulmonary disease.