MUC5B and idiopathic pulmonary fibrosis: Recently, we reported that a single nucleotide variant (SNV) rs35705950 in the upstream region of MUC5B gene, the strongest susceptibility variant to idiopathic pulmonary fibrosis (IPF) [11–13], was associated with ILD in the patients with rheumatoid arthritis (RA) in a multinational collaborative study [14].