Tay-Sachs Disease : HEXA Sequencing

Test Information

HEXA sequencing is a molecular test used to identify variants in the gene associated with Tay-Sachs Disease.

Turnaround Time

3 weeks

CPT Code(s)

81406

Cost

$1,000

Genes

Clinical Information

Tay-Sachs disease is an autosomal recessive lysosomal storage disorder caused by significantly reduced or absent activity of beta-hexosaminidase A. This deficiency results in accumulation of GM2 ganglioside which leads to the destruction of neurons in the brain and spinal cord. Although infants with Tay Sachs disease have normal developmental progress until the age of 3-6 months, regression becomes evident as the disorder progresses. Features of this condition include hypotonia, an increased startle reflex, inattentiveness, a retinal cherry-red spot, and loss of motor skills. Over time, seizures, hearing and vision loss, and spasticity develop, and most affected children die by the age of five. Tay Sachs disease occurs more frequently among specific groups including Ashkenazi Jewish, French Canadian, Pennsylvania Amish, and Louisiana Cajun populations.

Indications

Molecular testing is useful to confirm the diagnosis and to identify the disease causing mutations within a family to allow for carrier testing and prenatal diagnosis.

Methodology

Sanger Sequencing

Specimen Requirements

5 to 7 ml of peripheral blood collected in an EDTA (lavender top) tube is the preferred specimen type. The minimal blood needed for reliable DNA isolation is 3 ml. Extracted DNA, dried blood spots, and saliva are also accepted for this test.

Transport Instructions

The specimen should be kept at room temperature and delivered via overnight shipping. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Samples collected on Friday can be safely designated for Monday delivery.

Prenatal Testing Information

Prenatal diagnosis is available if the familial mutations are known. Additional fees for cell culture and maternal cell contamination may apply. Maternal cell contamination studies are required for all prenatal molecular tests. Contact the laboratory prior to sending a prenatal specimen.

Have Questions Need Support?

Call our laboratory at 1-800-473-9411 or contact one of our Laboratory Genetic Counselors for assistance.
Robin Fletcher, MS, CGC
Kellie Walden, MS, CGC

Sanger Sequencing
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