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Cystic Fibrosis Diagnosis

Test Information

Test Name: Cystic Fibrosis Diagnosis

Performing Lab: Molecular Diagnostic

Synonyms: CF Diagnosis, CF DNA Analysis for Diagnosis, Cystic Fibrosis DNA Analysis for Diagnosis.

Turnaround Time: 10 days

Additional Interpretation: Cystic Fibrosis is an autosomal recessive disorder due to mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Mutations in the CFTR gene lead to defective cellular chloride transport in affected individuals. CF is a multisystem disorder with a variable phenotype characterized by pulmonary disease, pancreatic insufficiency, liver disease, male infertility and abnormal swear gland function. Although over 1,000 mutations have been described in CF, phenotypic manifestation of disease can vary between individuals with the same genotype (1). Different ethnic groups have differences in the distribution of mutations associated with cystic fibrosis. Thus the positive and negative predictive value of CF mutations testing differs for different ethnic backgrounds. This test analyzes the 23 mutations recommended in the cystic fibrosis screening guidelines published by the American College of Medical Genetics and the American College of Obstetricians and Gynecologists (2). CFTR poly T tract, a string of thymidine bases located in intron 8 of the CFTR gene, can also be associated with CFTR-related disorders. 5T, 7T and 9T are the most common variants of the T tract. 7T and 9T are normal variants and 5T is a variably-penetrant mutation. Poly-T testing is performed as a reflex test when a R117H mutation is detected or an adult male is being evaluated for congenital bilateral absence of the vas deferens, a disease associated with the 5T variant. References: (1) American College of Medical Genetics and Genomics. Technical standards and guidelines for CFTR mutation testing. 2006 ed. (2) Moskowitz SM et al. CFTR-Related Disorders. GeneReviews 2001, updated 2008. Pagon RA, Adam MP, Ardiner HH et al, editors. Seattle (WA): University of Washington, Seattle; 1993-2014. (http://www.ncbi.nlm.nih.gov/books/NBK1250). Accessed July 14, 2016.

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Methodology: The eSensor technology (GenMark Diagnostics, Inc.) uses a solid-phase electrochemical method for determining the genotyping status of a defined panel of CF mutations. Genomic DNA is isolated and purified using laboratory standard methods and then amplified in a multiplex PCR reaction using specific primers and enzyme. The amplified DNA is converted to single stranded DNA via exonuclease digestion and is then combined with a signal buffer containing a pair of ferrocene-labeled, allele-specific oligonucleotide signal probes for each polymorphism. The mixture is loaded onto the eSensor cartridge, which contains single-stranded oligonucleotide capture probes bound to gold-plated electrodes and inserted into the XT-8™ instrument where the single stranded targets first hybridize to the matched signal probes and then hybridize to the complementary sequences of the capture probes. The genotype of each variant is determined by voltammetry, which generates specific electrical signals from the ferrocene-labeled, allele-specific signal probes.

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CPT Code: 81220



Result Information

No Information Available



Specimen & Collection Information

Specimen Name: Whole blood.

Container Type: Lavender-top EDTA tube.

Special Handling: Deliver peripheral blood promptly to the laboratory at 4ºC. DO NOT FREEZE.

Specimen Volume: 2.0 mL of peripheral whole blood.

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Specimen Transportation & Storage Information

Storage and Transport:Invert the tube containing the collected peripheral blood to mix with the anticoagulant. Deliver promptly to the laboratory at 4ºC. DO NOT SPIN. DO NOT FREEZE.