A combination treatment for cystic fibrosis that targets patients with a specific genetic mutation, has now been approved in the US for children six years and older. The treatment, Symdeko (tezacaftor/ivacaftor), targets a common mutation in the cystic fibrosis gene – the F508del mutation – which can lead to severe respiratory and digestive problems. The cystic fibrosis gene encodes the cystic fibrosis conductance transmembrane regulator (CFTR) protein which controls the movement of chloride and sodium in and out of cells in the human body.