CFTR and cystic fibrosis: Importantly, the fundamental difference between CF and CBAVD (as for other “CFTR-opathies”) is the distribution of genotypes: while individuals with CF present two severe mutations (~89%) or one severe and one mild mutation (~11%), those with CBAVD have either a severe and mild (~89%) or two mild (~12%) mutations, i.e., those with residual function and included in classes IV, V or VI [57,61,62].