CFTR and cystic fibrosis: At the end of the study period, after a mean follow up of 40.6 months (range 6–91.6), 39 (88.6%) out of 43 asymptomatic children remained in the CRMS/CFSPID category; on the other hand, 3 CRMS/CFSPID subjects progressed to CFTR-RD diagnosis for pancreatitis and one converted to CF for SC in pathological range.