Table 1.

Cystic fibrosis transmembrane conductance regulator (CFTR) class mutations and consequent impact on CFTR protein.

Class of Mutation	Impact on CFTR Protein and Example Mutations
I	Defect in protein synthesis, e.g., G542X, R553X, R1162X, W1282X
II	Defect in protein trafficking to cell membrane, e.g., G85E, I507del, F508del, N1303K
III	CFTR protein reaches the cell membrane but defect in channel gating, e.g., S549R, G551D, G1349D
IV	CFTR protein reaches the cell membrane but there is defective conductance, e.g., R117H, R334W, D1152H
V	Normal folding of the CFTR protein with normal function, but amount of protein made is insufficient, e.g., A455E, 2789+5G>A, 3849+10kbC>T
VI	CFTR protein is produced and is in the correct location but has reduced stability with rapid turnover, e.g., F508del, Q1411X