Cystic Fibrosis (CF) Profile, DNA Analysis and 5T Allele Genotyping

CPT: 81220
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Synonyms

  • CF Carrier

Test Includes

Detection of 32 CF mutations: G85E; ΔI507; R553X; 711+1G>T; 3659delC; R117H; ΔF508; R560T; 1078delT; 3849+10kbC>T; V520F; R1162X; 1717-1G>A; 3876delA; R334W; G542X; W1282X; 1898+1G>A; 3905insT; R347P; S549N; N1303K; 2183AA>G; 2184delA; R347H; S549R; 394delTT; 2789+5G>A; A455E; G551D; 621+1G>T; 3120+1G>A, plus 5T/7T/9T variants


Special Instructions

Whole blood tube should be sent to the lab unopened. It is preferable not to perform additional testing on original tubes prior to PCR testing. A completed screening questionnaire must accompany specimens. Call 800-345-4363 to request forms, or photocopy the Cystic Fibrosis Screening Questionnaire from the Genetics Appendix online.


Expected Turnaround Time

7 - 10 days



Specimen Requirements


Specimen

Whole blood or LabCorp buccal swab kit (buccal swab collection kit contains instructions for use of a buccal swab)


Volume

7 mL whole blood or LabCorp buccal swab kit


Minimum Volume

3 mL whole blood or two buccal swabs


Container

Lavender-top (EDTA) tube or LabCorp buccal swab kit


Storage Instructions

Maintain specimen at room temperature.


Causes for Rejection

Frozen specimen; hemolysis; quantity not sufficient for analysis; improper container; one buccal swab; wet buccal swab


Test Details


Use

Determine affected or carrier status for the 32 most common CF mutations (includes the mutation panel currently recommended by the ACMG and the ACOG); determine the presence of the 5T allele


Limitations

This assay detects as many as 90% of cystic fibrosis carriers in the Caucasian population. Within other ethnic groups, there may be higher or lower detection efficiency. Routine screening for the 5T allele in the cystic fibrosis (CF) gene as part of standard CF carrier screening is not recommended, since the goal of carrier screening is to identify couples at risk for having children with cystic fibrosis. The 5T allele is associated primarily with male infertility or atypical symptoms, although many individuals are asymptomatic.

Analysis of the 5T allele may be a useful adjunct to the standard CF panel of 32 mutations in patients with male infertility or idiopathic pancreatitis. Genetic counseling is recommended for any person testing positive for the 5T variant.


Methodology

Polymerase chain reaction (PCR) and a solution-phase multiplex allele-specific primer extension with subsequent hybridization to a bead array followed by fluorescence detection.


Additional Information

Cystic fibrosis (OMIM 602421) is a common genetic disorder resulting in chronic pulmonary and gastrointestinal/pancreatic disease. There is wide variability in clinical symptoms. CF is inherited in a recessive manner, which means that both parents must be carriers to have an affected child. When both parents are carriers, there is a 25% chance with each pregnancy that the child will be affected. Genetic counseling and CF molecular testing are recommended for the reproductive partners and at-risk family members of CF carriers.

LabCorp also offers Cystic Fibrosis (CF) Profile, 97 Mutations, CF plus® [450020] for 97 CF-causing mutations, which has specific utility for partners of known carriers, equivocal/diagnostic cases, high-risk couples (previous affected child) for whom at least one mutation remains unidentified after ACMG/ACOG profile testing, or for those persons whose ethnicity requires testing for less common mutations.


References

American College of Obstetricians and Gynecologists Committee on Genetics. ACOG Committee Opinion N° 486: Update on carrier screening for cystic fibrosis. Obstet Gynecol. 2011 Apr; 117(4):1028-1031. 21422883
Richards CS, Bradley LA, Amos J, et al. Standards and Guidelines for CFTR Mutation Testing. Genet Med. 2002; 4(5):379-391; erratum: 2002; 4(6):471.12394352
Watson MS, Cutting GR, Desnick RJ, et al. Cystic Fibrosis Population Carrier Screening: 2004 Revision of American College of Medical Genetics Mutation Panel. Genet Med. 2004; 6(5):387-391. Errata: 2004; 6(6):548, 2005; 7(4):286.15371902

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
480555 CF Scn+5T 480554 CF, Screen 21654-9
480555 CF Scn+5T 511943 PDF 51969-4
480555 CF Scn+5T 480556 Comment: 77202-0
480555 CF Scn+5T 480978 5T Allele Genotyping 34729-4
480555 CF Scn+5T 480977 Comment: 77202-0
480555 CF Scn+5T 511938 PDF 51969-4

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