CFTR and cystic fibrosis: For the subset of 169 patients with CF and two CFTR mutations Class I, II and/or III, in comparative analysis, there was a positive association with: (i) sweat chloride/sodium ratio (p < 0.001), (ii) sweat chloride values (p = 0.047), (iii) subject’s age at the time of the ST grouped by numerical order (p = 0.001).