CFTR and cystic fibrosis: For example, in cystic fibrosis causal mutations in human CFTR lead to altered glycosylation patterns of CFTR channel protein and channel trafficking defects in lung epithelial cells, and in long QT syndrome, coding mutations in human KCNE and KCNQ lead to reduced potassium ion channel glycosylation and reduced expression in the heart59, 60, 61, 62.