Susceptibility to CS-induced pulmonary fibrosis might be influenced by genetic variations in EMT-related genes, such as Snail Family Transcriptional Repressor 1 (SNAI1), Twist Family BHLH Transcription Factor 1 (TWIST1), and Zinc Finger E-Box Binding Homeobox 1 (ZEB1). This evidence concerns the gene TWIST1 and pulmonary fibrosis.