Bronchiectasis with or without elevated sweat chloride-1 (BESC1) is characterized by dilation of the airways arising from chronic bronchial inflammation accompanied by chronic cough, purulent sputum, and recurrent respiratory tract infections. Severity is variable, and some patients may be identified in adulthood and have normal respiratory function (Sheridan et al., 2005, Fajac et al., 2008). Genetic Heterogeneity of Bronchiectasis with or without Elevated Sweat Chloride Bronchiectasis with or without elevated sweat chloride-2 (BESC2; 613021) is caused by mutation in the gene encoding the alpha subunit of the epithelial sodium channel (SCNN1A; 600228) on chromosome 12p13, and BESC3 (613071) is caused by mutation in the gene encoding the gamma subunit (SCNN1G; 600761) on chromosome 16p12. Bronchiectasis and elevated sweat chloride associated with pancreatic exocrine dysfunction and infertility are also features of cystic fibrosis (CF; 219700), which is caused by mutation in the CFTR gene (602421).

Patients with bronchiectasis with or without elevated sweat chloride-2 (BESC2) have bronchiectasis and chronic bronchitis of varying severity. Pancreatic insufficiency may be present (Azad et al., 2009). For discussion of genetic heterogeneity in bronchiectasis with or without elevated sweat chloride, see BESC1 (211400).