Sandhoff Disease : HEXB Sequencing

Test Information

HEXB sequencing is a molecular test used to identify variants in the gene associated with Sandhoff Disease.

Turnaround Time

3 weeks

CPT Code(s)

81479

Cost

$900

Genes

Clinical Information

Sandhoff disease is an autosomal recessive lysosomal storage disorder caused by significantly reduced or absent activities of beta-hexosaminidase A and beta-hexosaminidase B. This deficiency results in accumulation of GM2 ganglioside which leads to the destruction of neurons in the brain and spinal cord. Infants with Sandhoff disease have normal developmental progress until the age of 3-6 months when developmental regression occurs. Features of this progressive condition include an increased startle reflex, a retinal cherry-red spot, seizures, vision and hearing loss, ataxia, and hepatoslenomegaly. Infantile Sandhoff disease typically results in death by age three. In rare cases, Sandhoff disease can occur with later onset, milder symptoms, and slower progression. Higher frequencies of Sandhoff disease have been reported among individuals with backgrounds including Northern Argentina Creole, the Metis population in Saskatchewan, and Lebanese descent.

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
Lucy's Story

Lucy's Story

When our daughter Lucy had a metabolic crisis at 7 days old, we were shocked and devastated to find out that she was born with a rare genetic disorder (MSUD). Her newborn screening results did not make it back in time to prevent the crisis, and no one at our local hospital was familiar with the disease. They did not know how to treat her. Calls were made to Greenwood Genetic Center to confirm her diagnosis...

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