The mutation in CFTR gene has been classified into five classes:

•  Class I mutation causes no CFTR protein output due to defective synthesis.

•  Class II mutation causes intracellular degradation of CFTR protein due to defective maturation of the protein.

•  Class III mutation causes defect in gating mechanism due to the blocked regulation.

•  Class IV mutation causes decreased chloride movement due to decreased conductance.

•  Class V mutation causes reduced wild-type CFTR protein production.

29.1 Table representing the nomenclature of CFTR mutations: