MUC5B and idiopathic pulmonary fibrosis: Therefore, to determine whether the MUC5B enhancer is in open chromatin in patient samples and whether MUC5B chromatin architecture can be decoupled from the secretory cell fate in IPF, we performed paired single-nucleus RNA-seq (snRNA-seq) and single-nucleus ATAC-seq (snATAC-seq) in lung tissue samples obtained from 2 patients with IPF (n = 1 GG and n = 1 TT genotype — i.e., homozygote for the risk allele) at rs35705950.