This is one of the most common genetic diseases. Almost 5% of people carry the abnormal recessive gene which must be present in both parents to cause the disease. The secretions of all the exocrine glands have abnormally high viscosity,but the most affected are those of the lungs,pancreas,intestines,biliary tract,and the reproductive system in males. Sweat glands secrete abnormally large amounts of salt during excessive sweating. In the pancreas, highly viscous mucus is secreted by the walls of the ducts and causes obstruction,parenchymal cell damage,the formation of cysts and defective enzyme secretion. In the newborns,intestinal obstruction may be caused by a plug of meconium peritonitis which is often fatal. In less acute cases there may be impairment of protein and fat digestion resulting on malabsorption,steatorrhoea and failure to thrive in infants. In older children:
A) Digestion of food and absorption of nutrients is impaired.
B) There may be obstruction of bile ducts in the liver,causing cirrhosis.
C) Bronchitis,bronchiectasis and pneumonia may develop.
