COL4A4 and chronic obstructive pulmonary disease: Our previous whole-exome sequencing study of three Uyghur families with COPD demonstrated that 72 mutations in 55 genes might be associated with COPD; these included rs15783G > A in the anoctamin 3 (ANO3) gene/mucin 15 (MUC15) gene, rs1800517G > A in the collagen type IV alpha 4 chain (COL4A4) gene, rs11960G > A in the ribosome binding protein 1 (RRBP1) gene, and rs5516C > G in the kallikrein 1 (KLK1) gene.