FISH, DiGeorge, Velocardiofacial Syndrome (VCFS)

Test Code

14610

CPT Codes
88271, 88273

Physician Attestation of Informed Consent

This germline genetic test requires physician attestation that patient consent has been received if ordering medical facility is located in AK, DE, FL, GA, IA, MA, MN, NV, NJ, NY, OR, SD or VT or test is performed in MA.

Includes

If this test is ordered on blood without routine G-band chromosome analysis, a Tissue Culture charge will be added, (CPT code: 88230). If results are not possible, the test order may be canceled and replaced with a Cytogenetics Communication.

Preferred Specimen

5 mL whole blood collected in a sodium heparin (green-top) tube

Minimum Volume

1 mL whole blood • 5 mg CVS

Other Acceptable Specimens

5 mL amniotic fluid collected in a sterile container • 5 mg CVS in culture media • Whole blood collected in: sodium heparin (royal blue-top), or sodium heparin lead-free (tan-top) tube

Instructions

Clinical history and reason for referral are required with test order.
3-5 mL whole blood collected in sodium heparin tube; or 5 mL amniotic fluid collected in sterile container or 5 mg CVS in culture media.
Specimen viability decreases during transit. Send specimen to testing lab for viability determination. Do not freeze. Do not reject.

Transport Temperature

Room temperature

Specimen Stability

Room temperature: See instructions
Refrigerated: See instructions
Frozen: See instructions

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)

Received frozen

Methodology
Fluorescence in situ Hybridization (FISH)

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by the U.S. Food and Drug Administration. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule

Set up: Mon-Sat; Report available: 6 days

Reference Range

See Laboratory Report

Clinical Significance

This test uses fluorescence in situ hybridization (FISH) technology to detect microdeletions in the chromosome 22q11.2 region when there is clinical suspicion of 22q11.2 deletion syndrome. Chromosome 22q11.2 deletions are associated with conditions including DiGeorge syndrome (DGS) and velocardiofacial syndrome (VCFS). 22q11.2 deletion syndrome cannot be detected by conventional or high-resolution chromosome analysis (karyotyping) [1,2].

Common clinical features associated with 22q11.2 deletion syndrome include congenital heart disease (64%); palate deformities (67%), especially cleft palate; learning difficulties (70%-90%); immune deficiency (77%); hypocalcemia (50%); gastrointestinal anomalies; renal anomalies (16%); skeletal abnormalities; and ocular abnormalities [3].

The FISH DGS/VCFS test is generally ordered for individuals with clinical suspicion of 22q11.2 deletion syndrome. This FISH test can also be performed on prenatal specimens, such as chorionic villus sampling and amniotic fluid specimens [4].

Note: Most deletions associated with 22q11.2 deletion syndrome can be detected with FISH. However, some affected individuals have smaller, atypical, nested deletions that cannot be detected with FISH but can be detected with chromosomal microarray analysis (CMA).

The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.

References
1. Novelli A, et al. Molec Cellular Probes. 1999;13(4):303-307.
2. International 22q11.2 Foundation. Deletion vs. Duplication. Accessed August 27, 2021. https://22q.org/what-is-22q/deletion-vs-duplication/
3. McDonald-McGinn DM, et al. 22q11.2 deletion syndrome. In: Adam MP, et al., ed. GeneReviews®. University of Washington; September 23, 1999. Accessed August 27, 2021. https://www.ncbi.nlm.nih.gov/books/NBK1523/
4. Driscoll DA. Genet Med. 2001;3(1):14-18.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Dr
Chantilly, VA 20153

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.