An in vivo study of CFTR-dependent sweat secretion in two CF patients with S945L/G542X and S945L/F508del genotypes also demonstrated the responsiveness of S945L to IVA reporting that IVA restored near-normal function to S945L-CFTR and supporting the use of IVA as a treatment for CF patients with this allele (62). This evidence concerns the gene CFTR and cystic fibrosis.