Cystic Fibrosis

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CYSTIC FIBROSIS

Gene Symbol: CFTR

Chromosomal Locus: 7q31.2
 
Protein: cystic fibrosis transmembrane conductance regulator
 
Pseudonyms: CF, cystic fibrosis transmembrane conductance regulator, ATP-binding cassette sub-family C, member 7, Congenital Absence of the Vas Deferens (CAVD)
 
TURNAROUND TIME: 8 days
 
2012 AMA Code: 81220
 
TESTING METHODOLOGY: This assay uses PCR and cleavase enzymes to recognize and cleave specific mutations in CFTR gene. This test examines a panel of 46 most common mutations in the US and European populations. The mutations in the ACOG/ACMG panel are included.
 
SPECIMEN REQUIREMENTS:
  • Collect: Prefer two 5ml whole blood EDTA (lavender top) tube.
  • Min. Collection: 0.7 ml whole blood EDTA.
  • Transport: blood EDTA at Room Temp shipped regular next day air (No Saturday delivery; store specimen at 4°C and ship Monday).
  • Stability: Ambient: up to 7 days; Refrigerated: 2 weeks. Frozen: unacceptable
  • Unacceptable Conditions: Serum. Frozen or severely hemolyzed blood. Clotted blood.
  • Prenatal testing: Direct: 5ml direct unspun amniotic fluid or 15mg CVS tissue with a backup flask growing. Culture: confluent T25 flask. Maternal blood sample is required for maternal cell contamination studies.
A Molecular Genetics Laboratory Test Requisition must accompany the specimen. Contact the Molecular Laboratory at 918-502-1721 to obtain further information.
Note: Counseling and informed consent are recommended for genetic testing. A consent form is available as a resource but not required.
 
INTERPRETATIVE DATA:
 
Incidence: 1 in 3,500 in the US and Northern European Caucasian populations are affected with Cystic Fibrosis. 1 in 20 of this same population are carriers of a Cystic Fibrosis mutation. Significant differences occur in other ethnic populations.
 
Inheritance: Autosomal recessive. However, a single mutation may lead to Congenital Absence of the Vas Deferens (CAVD) in some cases.
 
Disease Characteristics: Classical cystic fibrosis affects salt regulation in epithelia which affects secretory organs. Pulmonary disease resulting in lower airway inflammation and chronic endobronchial infection, progressing to end-stage lung disease is the most dramatic symptom. However, meconium ileums can occur at birth and pancreatic insufficiency leads to food malabsorption. Also more than 95% of males with CF are infertile. A milder form of CF, CAVD results in azoospermia and infertility but none of the more severe symptoms.
 
Molecular Genetic Mechanism: More than 1000 point mutations and small deletions are known to occur throughout the gene.
 
Clinical Sensitivity: The panel identifies >90% of the mutations in the US and Northern European Caucasian populations. Significant differences in detection rates occur in other ethnic populations.
 
Analytical Sensitivity: 99%
 
Test Limitations: This test only detects the 46 mutations that are in the panel. Rare diagnostic errors can occur due to primer / probe site mutations or rare polymorphisms.
 
INDICATIONS FOR USE:
  • Preconception screening of Caucasian couples as recommended by ACOG and ACMG.
  • Couples with a family history of CF that wish to undergo prenatal testing.
  • Newborns with failure to thrive or other suggestive clinical symptoms.
ADDITIONAL REFERENCES:
OMIM - Cystic fibrosis: http://omim.org/entry/219700
Genetics Home Reference - cystic fibrosis: http://www.ghr.nlm.nih.gov/condition/cystic-fibrosis
Genetics Home Reference - CFTR: http://www.ghr.nlm.nih.gov/gene/CFTR