Cystic Fibrosis Transmembrane Conductance
Congenital Bilateral Absence of the Vas deferens
Cystic Fibrosis Transmembrane Conductance Regulator
This test includes targeted testing to evaluate over 500 genetic variants including 23 pathogenic variants recommended by the American College of Medical Genetics and Genomics.
See Cystic Fibrosis Molecular Diagnostic Testing Algorithm for additional information.
Confirmation of a clinical diagnosis of cystic fibrosis
Reproductive risk refinement via carrier screening for individuals in the general population
Reproductive risk refinement via carrier screening for individuals with a family history when familial variants are not available
Identification of patients who may respond to cystic fibrosis transmembrane conductance regulator (CFTR) potentiator therapy
Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.
Collection Processing Instruction:
1. Invert several times to mix blood.
2. Send whole blood specimen in original tube. Do not aliquot.
To ensure minimum volume and concentration of DNA is met, the preferred volume of blood must be submitted. Testing may be canceled if DNA requirements are inadequate.
Specimen preferred to arrive within 96 hours of collection.
If there is a family history of cystic fibrosis, the known variant in the family should be supplied for best interpretation of results.
All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.
This assay will not detect all known disease-associated variants that cause cystic fibrosis (CF) or CFTR-related disorders. Therefore, the absence of a detectable variant does not rule out the possibility that an individual is a carrier of or affected with this disease.
A negative result does not eliminate the risk of carrier status for any of the included conditions, due to the possibility that the patient carries a variant that is not interrogated with this assay or the rare chance of a false-negative result for a tested variant. For tested variants, the negative predictive value of this screen is greater than 98%. The patient's residual risk to be a carrier after a negative screen is dependent on ethnic background and family history.
A positive control was not available for all variants targeted on this panel. For more information regarding availability of a positive control for each variant see Targeted Variants Interrogated by Cystic Fibrosis Variant Panel. The negative predictive value of these targets is unknown.
Rare variants (ie, polymorphisms) exist that could lead to false-negative or false-positive results. If results obtained do not match the clinical findings, additional testing should be considered.
All detected variants are evaluated according to American College of Medical Genetics and Genomics recommendations.(1) This assay was designed to specifically target known pathogenic or likely pathogenic variants. In rare cases, DNA variants of undetermined significance may be identified. The laboratory encourages healthcare providers to contact the laboratory at any time to learn how the status of a particular variant may have changed over time.
Multiple in-silico evaluation tools may have been used to assist in the interpretation of these results. Of note, the sensitivity and specificity of these tools for the determination of pathogenicity is currently unvalidated.
Test results should be interpreted in the context of clinical findings, family history, and other laboratory data. Misinterpretation of results may occur if the information provided is inaccurate or incomplete.
Bone Marrow transplants from allogenic donors will interfere with testing. Call Mayo Clinic Laboratories for instructions for testing patients who have received a bone marrow transplant.
An online research opportunity called GenomeConnect (genomeconnect.org), a project of ClinGen, is available for the recipient of this genetic test. This patient registry collects deidentified genetic and health information to advance the knowledge of genetic variants. Mayo Clinic is a collaborator of ClinGen. This may not be applicable for all tests.
Cystic fibrosis (CF), in the classic form, is a severe autosomal recessive disorder characterized by a varied degree of chronic obstructive lung disease and pancreatic enzyme insufficiency. The incidence of CF varies markedly among different populations, as does the genetic variant detection rate for the variant screening assay. To date, over 1500 variants have been described within the gene that causes CF, named cystic fibrosis transmembrane conductance regulator (CFTR). The most common variant, deltaF508, accounts for approximately 67% of the variants worldwide and approximately 70% to 75% in the North American White population. Most of the remaining variants are rare, although some show a relatively higher prevalence in certain ethnic groups or in certain atypical presentations of CF, such as congenital bilateral absence of the vas deferens (CBAVD). Genetic variants detected by this assay include the 23 variants recommended by the American College of Medical Genetics and Genomics as well as over 450 other variants.
Of note, CFTR potentiator therapies may improve clinical outcomes for patients with a clinical diagnosis of CF and at least one copy of a select subset of variants.
Detection rates for several ethnic and racial groups are listed in the table below. Note that interpretation of test results and risk calculations are also dependent on clinical information and family history.
*Rates are for classic CF. Rates are lower for atypical forms of CF and for CBAVD.
**Does not apply to individuals of Japanese ancestry.
An interpretive report will be provided.
All reported alterations are evaluated according to American College of Medical Genetics and Genomics recommendations.(1) Variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.
If testing is negative, and a diagnosis of cystic fibrosis is still suspected, consider CFTRZ / CFTR Gene, Full Gene Analysis, Varies.
Targeted testing for familial variants (also called site-specific or known mutation testing) is available for all genes on this panel under FMTT / Familial Mutation, Targeted Testing, Varies. Call 800-533-1710 to obtain more information about this testing option.