Table 2 Classification of the CFTR gene mutations (Lubamba et al. [12]; De Boeck et al. [13])
From: The determinants of survival among adults with cystic fibrosis—a cohort study
Class | Consequences | List of mutations attributed |
|---|---|---|
I | CFTR is not synthesized because of stop codons or splicing defects. | G542X, W1282X, R553X, 3950delT |
II | CFTR is synthesized but in an immature and is mostly degraded by the ubiquitin-proteasomal pathway. | F508del, N1303K |
III | CFTR is synthesized and transported to the plasma membrane, but its activation and regulation by ATPor cAMP are disrupted. | G551D, G178R, S549N, S549R, G551S, G970R, G1244E, S1251N, S1255P, G1349D |
IV | CFTR is synthesized and expressed at the plasma membrane, but chloride conductance is reduced. | R334W, G314E, R347P, D1152H |
V | CFTR synthesis or processing is partly defective. | 3849+ 10 kb C→T, 3272-26 A→G, 2789+5G→A |
Unclassified | All other mutations, including those unknown |