HEXA Gene Sequencing

Test Code

16612

CPT Codes
81406

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.

Preferred Specimen

5 mL whole blood collected in an EDTA (lavender-top) tube

Minimum Volume

3 mL

Other Acceptable Specimens

Cultured cells collected from amniotic fluid or cultured chorionic villi collected in two (x2) separate T-25 Flasks

Instructions

Whole blood: Normal phlebotomy procedure. Specimen stability is crucial. Store and ship room temperature immediately. Do not freeze.

Transport Temperature

Room temperature

Specimen Stability

Whole blood (preferred)
Room temperature: 14 days
Refrigerated: 14 days
Frozen: Unacceptable

Cultured cells or chorionic villi
Room temperature: 24 hours
Refrigerated: Unacceptable
Frozen: Unacceptable

Methodology
Next Generation Sequencing

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: As needed; Report available: 28 days following set up

Limitations

This test will identify greater than 99% of disease-causing mutations. It will also identify the known pseudodeficiency variants that are not associated with the disease but which lead to reduced enzyme activity when the standard enzyme assay is used to measure Hex A activity. Large rearrangements (deletions/insertions) are rare and not detectable by this test method. If no mutation is found by the testing procedure, it does not mean that the risk of carrying or developing TSD is not present. It simply means that this risk is significantly reduced.

Reference Range

See Laboratory Report

Clinical Significance

Tay-Sachs disease (TSD) is a progressive neurodegenerative disease. It is caused by pathogenic variants in the HEXA gene. Gene sequencing would be appropriate for individuals who have had a positive or equivocal Tay-Sachs enzyme carrier result and are negative for a panel of common pathogenic variants.

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.