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Cystic fibrosis (CF) is the most significant autosomal recessive disorder in the white population, occurring in approximately one in 2,500 live births. Approximately one in 20 whites carry a mutant CF gene allele (1). Only about one in 17,000 black infants are afflicted, and CF is very rare in Asian populations (2).
Historical references from the Middle Ages described children whose brows tasted of salt and who died prematurely (3), but it was not until 1938 that Andersen (4) described the clinical features of pancreatic fibrosis and pulmonary disease in detail and introduced the term cystic fibrosis (4). The term mucoviscidosis was coined in 1944 to reflect the importance of exocrine gland obstruction by inspissated mucous secretions in this disorder (5). CF was characterized as an autosomal recessive disorder in 1946 (6), and abnormal sweat gland electrolyte secretion was recognized in 1953 (7).
More recently, a defect in the permeability of epithelium to chloride ions was identified as the underlying physiologic abnormality in CF (8,9). Subsequently, the gene for CF was localized to the long arm of chromosome 7 (10,11). The gene and its product, a 1,480-amino acid protein regulating transmembrane ion transport, are termed the cystic fibrosis transmembrane conductance regulator (12). In CF, a defect in this regulator produces abnormally viscous luminal secretions, because the normal protein product represents an epithelial chloride channel that supplies luminal water by osmosis (13). The most common cause of CF is a three base-pair deletion called the DF508 mutation, which leads to the loss of a single phenylalanine in the protein product (14). Although this defect accounts for approximately 70% of CF mutant genes, over 230 other gene mutations that cause CF have been identified (15).
Pulmonary disease is the predominant cause of morbidity and death in CF patients, and its clinical, pathologic, and radiologic features in children and adults are detailed in a number of excellent reviews (16,17,18). Nevertheless, gastrointestinal manifestations remain important features of the clinical expression of CF. They are the most common symptoms suggesting the diagnosis of CF in infants and young children, and, because of the vastly improved survival of CF patients, are increasingly encountered by physicians caring for young adults (19). This article examines the clinical, pathologic, and radiologic features of the gastrointestinal manifestations of CF, including their differential diagnosis, treatment, and prognosis.
Introduction