- Must have the F508del-CFTR gene mutation in both alleles (Groups 1, 2, 3, 4, 5, 6). Group 7 subjects must have the F508del-CFTR mutation on 1 allele, and gating mutation G551D on the second allele and have been on their physician prescribed 150 mg KalydecoTM q12h (commercially available ivacaftor) for at least 28 days at the Screening Visit.