Background:
Cystic Fibrosis (CF) is a rare multisystem disease affecting epithelia of the respiratory tract, exocrine pancreas, intestine, hepatobiliary system, and exocrine sweat glands (Savant et al. 2024). The Cystic Fibrosis Foundation reports approximately 40,000 children and adults are living with cystic fibrosis in the U.S. and an estimated 105,000 people have been diagnosed with CF across 94 countries. CF is inherited in an autosomal recessive manner meaning an affected individual has inherited two disease causing variants in the gene CFTR. When an individual is diagnosed with CF, their parents are considered obligate carriers, meaning each pregnancy between the same parents has a 25% chance of resulting in an affected child. Additionally, unaffected siblings of an affected individual have a 50% chance of being carriers.
Targeted CFTR testing is recommended when there is a known familial CFTR variant or a relative with a molecular diagnosis of cystic fibrosis. This testing focuses specifically on the previously identified familial variant(s), allowing for accurate and efficient determination of carrier status. Results can inform reproductive risk assessment, guide clinical management, and enable appropriate testing of additional at risk family members.
Reasons for Referral:
- Positive family history with a known molecular CF diagnosis
- Testing for a known familial CFTR variant
Methodology:
Direct Sanger sequencing will be performed based on the specific variant of interest.
Specimen Requirements:
Blood: EDTA or ACD (Solution A or B):
- Adult: 5 mL
- Child: 5 mL
- Infant: 2-3 mL
Saliva: 2 ORAgene™ Saliva Collection Kits (OGR-500) used according to manufacturer instructions. Please contact KDL Client Services for a Saliva Collection Kit for patients that cannot provide a blood sample.
Assisted Saliva: 4 ORAgene™ Assisted Saliva Collection Kits (OGR-575) used according to manufacturer instructions. Please contact KDL Client Services for an Assisted Saliva Collection Kit for patients that cannot provide a blood sample.
Buccal Cells: 4 CytoSoft™ Cytology Brush (Medical Packaging CYB-1) used according to manufacturer instructions. Please contact KDL Client Services for a Buccal Collection Kit for patients that cannot provide a blood sample.
Skin Fibroblast: Punch Biopsy (Cell cultures will be prepared at KDL and used for testing), or 2 T-25 confluent flasks.
DNA: 1-2µg at a minimum of 100ng/µL (DNA must be extracted in a CLIA-certified laboratory or a laboratory meeting equivalent requirements as determined by the CAP and/or CMS).
Prenatal- Direct Amniotic Fluid (10-20mL)
- Direct CVS
- Direct POC
- Cultured Amniocytes (2 T-25 flasks)
- Cultured CVS (2 T-25 flasks)
- Cultured Fetal Tissue: Product of Conception (2 T-25 flasks)
- Cord Blood (1-2mL)
Notice Regarding Molecular Genetic Testing on Prenatal Specimens:Maternal cell rule-out testing will be performed on all prenatal specimens received. Please provide maternal blood (or saliva) in addition to the fetal specimen. Additional charges apply for the maternal cell rule-out test.
For routine testing of blood, saliva and buccal swabs, KDL does NOT accept samples from patients within two (2) weeks of a packed cell/platelet transfusion or within four (4) weeks of a whole blood transfusion. For extraordinary circumstances, where testing must be performed within the above windows, please contact our lab.
A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES. Please include detailed clinical information, including ethnicity, clinical history, and family history.
Test Performed (Days):
Weekly
Turn Around Time:
14-21 days
Shipment Sensitivity Requirements:
- Package and ship specimen to remain cold, but not frozen.
- Ship via overnight express, using the FedEx priority overnight label provided.
- Contact Client Services for shipping kits and instructions at (855) 535-1522.
References:
- Savant A, Lyman B, Bojanowski C, et al. Cystic Fibrosis. 2001 Mar 26 [Updated 2024 Aug 8]. In: Adam MP, Feldman J, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2025. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1250/
Additional Info:
Please note on the requisition form the specific mutation(s) for which testing is requested; also note other family members tested in our laboratory and report numbers if known. If testing was performed on the proband (affected family member) outside of our laboratory, please include a copy of that clinical report.