Congenital Disorders of Intestinal Electrolyte Transport.

Congenital diarrheal disorders (CDD) represent a group of rare chronic enteropathies characterized by a heterogeneous etiology, with a typical onset early in the life. In the context of CDD, a subset consists in congenital disorders of intestinal electrolytes transport, a class of inherited disorders related to a defect in intestinal transepithelial ion transport. Most of these disorders display similar clinical presentation. For many of these conditions, severe chronic diarrhea represents the main clinical manifestation, while in others diarrhea is only a component of a more complex multiorgan or systemic disease. Frequently, diarrhea leads to severe dehydration and metabolic acidosis. In the vast majority of cases, appropriate therapy must be started immediately to prevent dehydration and long-term, and sometimes life-threatening, complications. The diagnosis of these disorders is rather complex, but in most cases, the disease gene is known. Thus, molecular analysis has become a major advantage in the difficult diagnostic approach to a patient with suspected congenital disorders of intestinal electrolytes transport. This group of disorders includes congenital chloride diarrhea, congenital sodium diarrhea, familial diarrhea syndrome, and cystic fibrosis that are the main subjects of this chapter.