Of the 1700 mutations identified in CFTR, the most common is the deletion mutant F508 (a class 2 mutation) which results in impaired trafficking of CFTR and reduces its incorporation into the plasma membrane causing cystic fibrosis (reviewed in [http://www.ncbi.nlm.nih.gov/pubmed/21108631?dopt=AbstractPlus]). The gene discussed is CFTR; the disease is cystic fibrosis.