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Cystic Fibrosis and Congenital Absence of the Vas Deferens.


GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2019.
2001 Mar 26 [updated 2017 Feb 2].

Author information

Division of Pulmonary and Sleep Medicine, Seattle Children's Hospital, University of Washington School of Medicine, Seattle, Washington
DNA Diagnostic Laboratory, Johns Hopkins University School of Medicine, Baltimore, Maryland
Department of Laboratories and Pediatric Laboratory Utilization Guidance Services, Seattle Children's Hospital, Seattle, Washington
Department of Obstetrics and Gynecology, University of Washington School of Medicine, Seattle, Washington
Institute of Genetic Medicine, Departments of Pediatrics and Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland



Cystic fibrosis (CF) is a multisystem disease affecting epithelia of the respiratory tract, exocrine pancreas, intestine, hepatobiliary system, and exocrine sweat glands. Morbidities include progressive obstructive lung disease with bronchiectasis, frequent hospitalizations for pulmonary disease, pancreatic insufficiency and malnutrition, recurrent sinusitis and bronchitis, and male infertility. Pulmonary disease is the major cause of morbidity and mortality in CF. Meconium ileus occurs at birth in 15%-20% of newborns with CF. More than 95% of males with CF are infertile. Congenital absence of the vas deferens (CAVD) is generally identified during evaluation of infertility or as an incidental finding at the time of a surgical procedure. Hypoplasia or aplasia of the vas deferens and seminal vesicles may occur either bilaterally or unilaterally. Testicular development and function and spermatogenesis are usually normal.


The diagnosis of CF is established in a proband with one or more characteristic phenotypic features and evidence of an abnormality in cystic fibrosis transmembrane conductance regulator (CFTR) function (e.g., 2 elevated sweat chloride values, biallelic CFTR pathogenic variants, or transepithelial nasal potential difference measurement characteristic of CF). The diagnosis of CF is established in an infant with elevated trypsinogen on newborn screening and identification of biallelic CFTR pathogenic variants or an elevated sweat chloride. The diagnosis of CAVD is established in a male with azoospermia and absence of the vas deferens on palpation or identification of biallelic CAVD-causing CFTR pathogenic variants.


Treatment of manifestations: Treatment of respiratory complications using inhaled dornase alfa, inhaled hypertonic saline, antibiotics, anti-inflammatory agents, ivacaftor, ivacaftor/lumacaftor combined therapy, lung or heart/lung transplant; topical steroids, antibiotics and/or surgical intervention for nasal/sinus symptoms; treatment of exocrine pancreatic insufficiency using oral pancreatic enzyme replacement, special infant formulas, supplemental nutrition, fat-soluble vitamin supplements and zinc; management of CF-related diabetes mellitus (CFRD) by an endocrinologist; surgical management for meconium ileus; oral ursodiol for biliary sludging/obstruction, liver transplant when indicated; assisted reproductive technologies (ART) for male infertility. Prevention of primary complications: Airway clearance techniques, dornase alpha, hypertonic saline, antibiotics to prevent chronic airway infection, immunizations including anti-RSV monoclonal antibody; physical activity to maintain bone health and improve airway clearance; nutritional support for pancreatic insufficiency; extra salt and water in hot, dry climates. Surveillance: Frequent visits to CF care providers to monitor for changes in symptoms and physical examination; cultures of respiratory tract secretions at least four times yearly; pulmonary function studies, chest radiographic examination, annual electrolytes, fat-soluble vitamin levels and IgE levels; bronchoscopy and chest CT examination when indicated; monitor weight gain and caloric intake in infants until age six months; fecal elastase when indicated; annual oral glucose tolerance test in individuals older than age ten years; evaluation of bone mineral density starting in adolescence; annual liver function tests and liver ultrasound to monitor progression of liver disease. Agents/circumstances to avoid: Respiratory irritants; individuals with respiratory infections; dehydration. Evaluation of relatives at risk: Molecular genetic testing of at-risk sibs if the pathogenic variants in the family are known or sweat chloride testing of at-risk sibs if the pathogenic variants in the family are not known, to identify as early as possible those who should be referred to a cystic fibrosis center for initiation of treatment and preventive measures. Therapies under investigation: Prophylactic ursodiol therapy; CF corrector VX-661; inhaled dry powder mannitol; CFTR gene therapy.


CF and CAVD are inherited in an autosomal recessive manner. At conception, each sib of an affected individual with CF and brothers of a male with CAVD have a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier. Carrier testing for at-risk relatives and prenatal testing for pregnancies at increased risk are possible if the CFTR pathogenic variants in the family are known.

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