MUC4 and lung disorder: The latest and largest study, a meta-analysis of 6,365 French and North-American CF patients, identified five regions outside the SLC26A9 locus that displayed significant association with variation in lung disease: the locus of the mucin genes MUC4 and MUC20, of the solute carrier genes SLC9A3 and SLC6A14, and of the HLA Class II region (Corvol et al., 2015).