Understanding CF

People with cystic fibrosis (CF) cannot control the levels of salt and water in their body cells properly, so their body fluids are thicker than usual. They have more salt in their sweat, which doctors can measure to diagnose the condition (the 'sweat test'). In 1989, researchers discovered that people with CF have no working version of a gene that usually makes a protein that controls salt levels.

DNA analysis of cystic fibrosis. Each lane shows a different person's DNA: the upper band is unaffected (left arrow) and the lower band is affected (right arrow). The parents are unaffected carriers, the child on the right is affected and the child on the left is unaffected. Sally Genet, North Thames Regional Genetics Service