Cystic Fibrosis

Cystic fibrosis (CF) is a chronic genetic condition involving multiple organ systems. Involving mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, two defective alleles cause the body to produce abnormally thick, sticky mucus that clogs the lungs and leads to life-threatening infections. Classic CF primarily involves the respiratory and digestive systems and may have a range of clinical severity. Pulmonary symptoms often include lower airway inflammation, chronic cough, sinusitis, and recurrent infections. People with CF have a variety of other symptoms including high sweat chloride levels, persistent coughing, wheezing or shortness of breath, and excessive appetite but poor weight gain. Thick secretions also obstruct the pancreas and prevent digestive enzymes from reaching the intestines to help break down and absorb food. Digestive symptoms often include meconium ileus (bowel obstruction in a newborn baby), pancreatic insufficiency resulting in malabsorption and/or failure to thrive, and hepatobiliary disease. CFTR mutations may also lead to congenital bilateral absence of the vas deferens (CBAVD) and infertility. Sweat chloride testing has a clinical sensitivity of 90% in classic CF and is considered the gold standard for diagnosis. Individuals with non-classic CF may have clinical findings limited to a single organ system, such as idiopathic pancreatitis, bilateral absence of the vas deferens, nasal polyposis, or bronchiectasis. Non-classic CF often presents in adulthood and may not decrease life expectancy. Sweat chloride values in individuals with non-classic CF are often borderline, but may also be elevated or in the normal range.