Cystic Fibrosis Expanded Mutation Analysis – CFplus

CPT 81220
Synonyms CF Carrier; CF Testing;

Test Details

Turnaround Time

7 - 10 days Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Use

CFplus is an expanded mutation panel that tests for 97 mutations and provides high detection rates for the pan-ethnic US population.

Special Instructions

Prenatal testing: Integrated Genetics clients should call 800-848-4436 to speak to a laboratory genetic coordinator before collecting any specimens. In some circumstances, specimens from other family members may be required. All prenatal specimens (including cord blood) must be accompanied by a maternal blood or mouthwash specimen for analysis of possible maternal cell contamination. Discard first 2 mL; then 10 mL amniotic fluid in 15 mL orange-top polypropylene tube, 10-15 mg chorionic villi in laboratory-provided screw-top tubes with sterile transport medium or 1 T-25 flask of confluent cells. Additional sample must be obtained for back-up culture at one of our cytogenetics laboratories or another facility. If additional testing is desired, more amniotic fluid is needed. For example, chromosome analysis requires an additional 15-25 mL (see Cytogenetics – Amniotic Fluid Chromosome Analysis test page) and AFAFP requires an additional 2 mL (see Amniotic Fluid Alpha-Fetoprotein - AFAFP test page).

Test Includes

Testing for 97 cystic fibrosis mutations, including all of the mutations currently recommended by the ACMG and ACOG

Limitations

False positive or false negative results may occur for reasons that include: genetic variants, technical handling, blood transfusions, bone marrow transplantation, mislabeling of samples, or erroneous representation of family relationships.

Methodology

DNA is isolated from the sample and tested for the 97 CF mutations listed. Regions of the CFTR gene are amplified enzymatically and subjected to a solution-phase multiplex allele-specific primer extension with subsequent hybridization to a bead array and fluorescence detection. Some mutations are then specifically identified by bidirectional dideoxysequencing. Discriminates between p.F508del and the following polymorphisms: F508C, I506V, and I507V p.F508C, p.I506V, and p.I507V.

Additional Information

The American College of Obstetricians and Gynecologists recommends that because it is becoming increasingly difficult to assign a single ethnicity it is reasonable to offer CF carrier screening to all pregnant patients, provided that women are aware of carrier risks and of test limitations. If both parents are found to be carriers, prenatal diagnosis by CVS or amniocentesis is available. Indications for CF testing include: all pregnant and preconception couples, individuals with a history of CF, symptomatic or screen-positive infants too young for sweat testing; symptomatic children with negative or equivocal sweat tests; congenital bilateral absence of the vas deferens (CBAVD); and idiopathic pancreatitis.

Specimen Requirements

Information on collection, storage, and volume

Specimen

Whole blood, mouthwash (see specimen kit for detailed instructions), dried blood spot kit, amniotic fluid, chorionic villi, cultured amniotic fluid, cultured chorionic villi.

Volume

Postnatal: 4 mL whole blood or mouthwash or 3 dried blood spots/Prenatal: 10 mL amniotic fluid in orange-top polypropylene tube, 10-15 mg chorionic villi in laboratory provided screw-top tubes with sterile transport medium or one T-25 flask of confluent cells.

Container

Lavender-top (EDTA) tube or yellow-top (ACD-A) tube or mouthwash kit or dried blood spot kit

Storage Instructions

Maintain specimen at room temperature

Causes for Rejection

Frozen specimen; hemolysis; quantity not sufficient for analysis; improper container; unlabeled or mislabeled specimen

Collection

Dried blood spots: Collect on Integrated Genetics provided filter paper/test requisition. Fill a minimum of three circles completely with blood. Please Note: If prenatal carrier screening for cystic fibrosis is ordered in conjunction with first trimester screening all six circles should be filled. Mouthwash collection: Patient should not eat, drink, smoke or chew gum for at least one hour prior to collection. (See specimen kit for detailed instructions). Mouthwash samples can be sent when ordering up to two tests. When ordering more than two tests, blood samples are required. 10 mL of Scope® mouthwash that has been swished vigorously for at least 1 minute. Collect in orange-top 50 mL polypropylene tube.