Table 1 Summary of mutation classes
Mutation classBasic defectCFTR protein abnormalityExamples
Old nameNew name
INonsense mutationsPremature termination codon leads to a truncated protein with no functionG542XGly542X
IITrafficking defectMisfolding causes the protein to fail to be trafficked to the apical surface of the cellΔF508Phe508del
IIIGating defectNormal quantities of CFTR protein reach the cell membrane but the channel remains closed preventing normal functionG551DGly551Asp
IVDecreased conductivityProtein reaches the apical surface but conductance across the channel is poor due to the abnormal conformationR117HArg117His
VSplicing defectDecreased amounts of CFTR reach the apical membrane The CFTR that does, probably functions normally; hence, many patients with these mutations have a milder phenotype38949+10kbC>Tc.3717+12191C>T
VIDecreased half-lifeCFTR is functional but half-life is decreased leading to overall decreased amount of CFTR present at the cell surface and it may impair regulation of other channelsQ1412XGln1412X