Some of these mutations will lead to pancreatic insufficiency, whereas the others are associated with adequate pancreatic functions. Mutant alleles associated with pancreatic sufficiency seem to have a dominant effect over alleles that cause pancreatic dysfunction. The pathogenetic event leading to pancreatic insufficiency is presumed to be either the partial or the complete occlusion of ductal and saccular structures by inspissated secretions. Mild inflammation may be present, and eventually, atrophy occurs. In most cases, the cells of the islets of Langerhans are preserved until late in the course of the illness, although an underlying disorder common to both exocrine and endocrine cells may be present.
Pancreatic involvement begins in utero.
Probably about 90 percent of patients with cystic fibrosis eventually display evidence of pancreatic insufficiency. Early in the disease course, pancreatic insufficiency may be inapparent or mild, but it tends to be progressive. Flatulence may be a prominent symptom. Malnutrition and deficiencies of lipid-soluble vitamins, especially vitamin E, may occur. Some patients, especially those with residual pancreatic function, experience abdominal pain caused by attacks of acute pancreatitis.