CFTR and cystic fibrosis: In this subgroup, 22 different CF-causing variants accounted for 118 alleles (52.2%), and 14 different VCC variants accounted for 74 alleles (32.7%), while 28 alleles (12.4%) had no known clinical consequences (variants not present in CFTR mutation database and/or in CFTR2 database or with unknown clinical consequences or unidentified), and 6 (2.7%) alleles were classified by CFTR2 database as No-CF variants.