Cystic fibrosis, also called fibrocystic disease of the pancreas, and mucoviscidosis, is a genetically determined disease of infants, children, and young adults. Most of its many manifestations result from the abnormally viscous mucus, which interferes with pulmonary function, and the insufficient production of pancreatic digestive enzymes, which causes nutritional deficiencies and developmental retardation.

Etiology

Among Caucasians, cystic fibrosis (CF) is the most common fatal disease having an autosomal recessive inheritance. Despite the primary involvement of several organs, the disease is caused by a single defective gene that is located on chromosome 7 and is carried by about 4 percent of the Caucasian population. Its expression is similar in both sexes.

Clinical Manifestations

CF manifests itself at birth in about 8 percent of cases through mechanical obstruction of the small intestine by the secretion of abnormally viscous mucus (meconium ileus). Symptoms of insufficient secretion of exocrine (noninsulin) digestive enzymes by the pancreas appear during the first year of life in 90 percent of cases. The development of such symptoms indicates that pancreatic function is less than 10 percent of normal; and the more severe the deficiency of pancreatic enzymes, the more severe the fecal excretion of undigested fat, usually as diarrhea. As much as 80 percent of dietary fat may be lost, thus partially explaining malnutrition. Loss of undigested nutrients can be corrected only partially by treatment with pancreatic enzyme tablets. Pulmonary disease is responsible for most of the debility and mortality. Onset occurs in the first 2 years of life in at least 75 percent of cases, and by the age of 6 years in most of the remaining cases.