He et al. [71] found that the expression of protein arginine methyltransferase 6 (PRMT6) and asymmetric di-methylation of histone H3 arginine 2 (H3R2me2a) were significantly decreased in the lung tissues of patients with COPD who continue to smoke and CSE-induced mice. This evidence concerns the gene PRMT6 and chronic obstructive pulmonary disease.