As shown in Figure 3, 10 of the 16 leukocyte samples analyzed for CFTR activity were responsive (Figure 3A) and six were unresponsive (Figure 3B) to the treatment with VX770 (for mutations see Supplementary Materials Table S1: CFTR mutations of the CF patients eligible for Ivacaftor therapy). This evidence concerns the gene CFTR and cystic fibrosis.