Cystic Fibrosis

What Your Test Results Mean:

Carriers typically show no symptoms of cystic fibrosis; however, carriers are at an increased risk of having a child with cystic fibrosis. Risk for the current or future pregnancies is dependent on your partner’s carrier status.

Disease Explained:

Cystic fibrosis is an inherited condition that affects the lungs, pancreas, liver, and male reproductive system. Some males may not develop lung or gastrointestinal symptoms of the disease and will only present with male infertility caused by congenital absence of the vas deferens (CAVD). Both cystic fibrosis and CAVD are caused by abnormalities in the cystic fibrosis transmembrane conductance regulator (CFTR). Individuals with cystic fibrosis are unable to properly regulate epithelial chloride and sodium channels, leading to an increased risk for lung infections, digestion problems, diarrhea, poor growth and male infertility.

Management of disease is lifelong to prevent pulmonary complications and enhance weight gain. The majority of individuals with cystic fibrosis will require oral pancreatic enzyme replacement. With advances in treatment and appropriate management, individuals with cystic fibrosis typically live into their late thirties. Individuals with CAVD may conceive children through assisted reproductive technologies.

How the Genetics Works:

The clinical features of cystic fibrosis disease can be explained by pathogenic variants in the CFTR gene. In general, individuals have two copies of the CFTR gene. Carriers of cystic fibrosis disease have a single variant in one copy of the CFTR gene while individuals with cystic fibrosis disease have variants in both copies of their genes, one inherited from each parent.

Cystic Fibrosis Carrier Screening Test

Abeliovich et al. (1992). Screening for five mutations detects 97% of cystic fibrosis chromosomes and predicts a carrier frequency of 1:29 in the Jewish Ashkenazi population. Am J Hum Genet, 51:951-956.
American College of Obstetricians and Gynecologists, Committee on Genetics (2011). Committee Opinion Number 486. Update on Carrier Screening for Cystic Fibrosis. Obstetrics and Gynecology, 117(4):1028-1031.
Augarten et al. (2008). The changing face of the exocrine pancreas in cystic fibrosis: the correlation between pancreatic status, pancreatitis and cystic fibrosis genotype. Eur J Gastro Hepatology, 20(3):164-168.
Braekeleer and Ferec (1996). Mutations in the cystic fibrosis gene in men with congenital bilateral absence of the vas deferens. Mol Hum Reprod, 2(9):669-677.
Bobadilla et al. (2002). Cystic Fibrosis: A Worldwide Analysis of CFTR Mutations–Correlation with Incidence Data and Application to Screening. Human Mutation, 19:575-606.
Castellani et al. (2008). Consensus on the use and interpretation of cystic fibrosis mutation analysis in clinical practice. J Cystic Fibrosis, 7:179-196.
Casals et al. (2000). Gender-sensitive association of CFTR gene mutations and 5T allele emerging from a large survey on infertility. Human Reproduction, 15(17):1476-1483.
Centers for Disease Control and Prevention. Population-Based Prenatal Screening for Cystic Fibrosis via Carrier Testing.
Cystic Fibrosis Centre at the Hospital for Sick Children in Toronto. Cystic Fibrosis mutations database.
Estivill et al. (1997). Geographic Distribution and Regional Origin of 272 Cystic Fibrosis Mutations in European Populations. Human Mutation, 10:135-154.
Ferec et al. (1995). Neonatal screening for cystic fibrosis: result of a pilot study using both immunoreactive trypsinogen and cystic fibrosis gene mutation analyses. Human Genetics, 96:542-548.
Feuillet-Fieux et al. (2004). Novel CFTR mutations in black cystic fibrosis patients. Clin Genetics, 65(4):284-287.
Grebe et al. (1994). Genetic Analysis of Hispanic Individuals with Cystic Fibrosis. Am J Hum Genet, 54:443-446.
Goetzinger and Cahill (2010). An Update on Cystic Fibrosis Screening. Clin Lab Med, 30:533-543.
Grody et al. (2001). Laboratory standards and guidelines for population-based cystic fibrosis carrier screening, ACMG policy statement. Genet Med, 3(2):149-154.
Heim et al. (2001). Improved detection of cystic fibrosis mutations in the heterogeneous U.S. population using an expanded, pan-ethnic mutation panel. Genet Med, 3(3):168-176.
Kazazian, Haig (1994). Population Variation of Common Cystic Fibrosis Mutations. Human Genetics, 4:167-177.
Leeds Method of Management. (2008). The genetics of Cystic Fibrosis [online]. Leeds Regional Adult and Paediatric Cystic Fibrosis Units, St James’s University Hospital, Leeds, UK. Available from
Macek et al. (1997). Identification of Common Cystic Fibrosis Mutations in African-Americans with Cystic Fibrosis Increases the Detection Rate to 75%. Am J Hum Genet, 60:1122-1127.
Monaghan et al (2004). Preconception and prenatal cystic fibrosis carrier screening of African American reveals unanticipated frequencies for specific mutations. Genet Med 6(3):141-144.
Morea et al. (2005). Gender-sensitive association of CFTR gene mutations and 5T allele emerging from a large survey on infertility. Mol Hum Reprod, 8:607-614.
Palomaki et al. (2002). Updated assessment of cystic fibrosis mutation frequencies in non-Hispanic Caucasians. Genet Med, 4(2):90-94.
Palomaki et al. (2004). Clinical sensitivity of prenatal screening for cystic fibrosis via CFTR carrier testing in a United States panethnic population. Genet Med, 6(5):405-414.
Perez et al. (2007). CFTR gene analysis in Latin American CF patients: Heterogeneous origin and distribution of mutations across the continent. J Cystic Fibrosis, 6:194-208.
Rohlfs et al. (2011). Cystic Fibrosis Carrier Testing in an Ethnically Diverse US Population. Clin Chem, 57(6):841-848.
Schwartz et al. (1996). Cystic Fibrosis Mutation Analysis: Report from 22 UK Regional Genetics Laboratories. Human Mutation, 3:326-333.
Scotet et al. (2000). Neonatal screening for cystic fibrosis in Brittany, France: assessment of 10 years’ experience and impact on prenatal diagnosis. Lancet, 356:789-794.
Sugarman et al. (2004). CFTR mutation distribution among U.S. Hispanic and African American individuals: Evaluation in cystic fibrosis patient and carrier screening populations. Genet Med, 6(5):392-399.
Watson et al. (2004). Cystic fibrosis population carrier screening: 2004 revision of American College of Medical Genetics mutation panel. Genet Med, 6(5):387-391.
World Health Organization (WHO) (2002). The Molecular Genetic Epidemiology of Cystic Fibrosis. Report of a joint meeting of WHO/ECFTN/ICF(M)A/ECFS.
Additional Cystic Fibrosis References: Available upon request

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