The gene affected by CF is the code for the way the body controls the movement of salt and water in and out of cells. In people affected by CF this does not occur as it should, and the body’s secretions are thicker and stickier than they should be. This occurs in many organs of the body, but the effects are  particularly noticeable in the lungs and in the digestive system.    The build up of sticky secretions (mucus) in the breathing tubes (bronchi) tend to predispose people with CF to coughs and chest infections. Over long periods of time this can lead to lung damage and a reduction in lung function. In the digestive system the sticky secretions tend to block the ducts in the pancreas. This means that the pancreas cannot properly secrete the enzymes needed to break down the food when eaten by people with CF. This can lead to fatty, smelly stools and to poor growth. The sticky mucus can affect other parts of the body too. Some older people with CF develop CF related diabetes and they need additional treatment to manage this.   Other problems experienced, mostly by adults, include sinusitis, nasal polyps, osteoporosis, arthritis and liver disease.