Cystic fibrosis is an inherited condition with a fatal outcome and the most common type of these conditions in populations of Caucasian origin. It is inherited as two recessive genes, one from each partner, although these carriers show no sign of illness. The genetic error affects the exocrine glands and most typically gives chronic respiratory tract infections. A large number of bodily organ systems are involved in this disease but the end of a patient's life is almost always secondary to severe lung disease.

The genetic abnormality affects the thickness of the body's mucus, making it stickier which in turn makes it more vulnerable to bacterial infection. Thickened secretions can be present in the respiratory tract which makes them difficult to clear, but they are also present in the pancreas, sweat glands and the digestive tract. Initially the lungs are normal but soon after birth an infection develops at some time and the cycle of infection and inflammation is set up along with a continual presence of specific bacteria in the lungs. Gradually the lung membranes become thickened and less efficient, leading eventually to respiratory failure.

The gastrointestinal tract can be obstructed or otherwise negatively affected by thicker mucus and this reduces the efficiency of absorption of nutrients from the food, often an early sign of problems as a baby fails to thrive, i.e. does not grow as expected. Obstruction from adhesions can occur and surgical removal of part of the gut be needed, further limiting absorption of nutrients. Reduced efficiency of the pancreatic enzymes occurs and if insufficiency of the pancreas develops then fat soluble vitamins such as K, E, D and A are poorly absorbed.

The incidence of cystic fibrosis makes it the most frequently occurring lethal genetic condition, inherited via a recessive gene trait. In populations of white European origin the typical frequency is one in 3200 births while in populations in Asia this may be one in 90,000 only. 37 years is the typical age of survival with male patients living for a significantly longer period than female patients. Progression of the lung abnormalities goes from bronchitis to bronchiectasis and then on to heart failure with end stage disease of the lungs. The disease is very variable in how it progresses, the age of the patient at presentation, the severity of the symptoms and the manner of disease progression.

Gallbladder inflammatory changes and the presence of gallstones have a higher incidence in patients with cystic fibrosis. Secondary sexual characteristics and the onset of puberty are typically delayed and males are infertile due to absence of a vas deferens, while female patients may have reduced fertility to some degree. Progression of lung disease is worse in patients who come from the lower socioeconomic levels. Overall the severity of lung symptoms is less in male patients than in female patients, with females suffering worse lung prognosis and a lower life expectancy.

Due to the complexity of cystic fibrosis and the involvement of many bodily systems the most effective diagnosis and management of this condition is performed by a multidisciplinary team in a specialist centre. Apart from the initial diagnosis and baseline measurements, followed by the plan of treatment, there are many other parts to the overall management. Education of the patient or the parents is of vital importance as adherence to the treatment regime is so important if the patient is to make the best of their remaining life. Counselling may be employed as patients face the difficulties of managing a lifelong condition. Physiotherapy instruction for airway clearance technique is also vital, with instruction on how to use inhalers and nebulisers.

Surgery may be required to treat respiratory complications such as bringing up large amounts of blood in the sputum or collapses of the lung. Complications in the gastrointestinal system such as gut obstruction may also be managed surgically. Transplants can treat lung disease of the end stages, although they do not seem to increase the length of life but increase the quality of life. A normal diet can be taken but patients should increase their mineral and vitamin intake with more energy and fats. Chronic inflammation increases demands for energy and along with poor nutrient absorption this means intake can be supplemented.