Specifically, loss-of-function mutations of the CFTR gene are the root cause of cystic fibrosis (CF)5; conversely, numerous studies have linked upregulated CFTR activity to secretory diarrhea and polycystic kidney disease, resulting from excessive salt/water transport into the intestinal lumen and kidney cysts, respectively6–9. The gene discussed is CFTR; the disease is cystic fibrosis.