Tay-Sachs/Sandhoff Disease : Beta-hexosaminidase Enzyme Analysis

Test Information

This biochemical test is a quantitative measurement of beta-hexosaminidase A and beta-hexosaminidase B enzyme activity and can be used as a 1st tier test for patients with a clinical suspicion of Tay-Sachs/Sandhoff Disease. Demonstration of deficient beta-hexosaminidase enzyme activity is considered the gold standard to confirm a diagnosis of Tay-Sachs/Sandhoff disease.


Turnaround Time

2 weeks

CPT Code(s)

83080

Cost

$200


Enzymes

Beta-hexosaminidase

Clinical Information

Tay Sachs disease is an autosomal recessive lysosomal storage disorder (LSD) 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.

Sandhoff disease is clinically indistinguishable from Tay Sachs disease, but it results from deficiencies in both beta-hexosaminidase A and hexosaminidase B. 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

This test can be used to confirm a suspected diagnosis of Tay Sachs or Sandhoff disease.

Methodology

4-methylumbelliferyl substrate

Specimen Requirements

Enzyme activity can be measured in plasma or leukocytes. For whole blood, please send 5-7 ml of whole blood in a green top (sodium heparin) tube OR plasma can removed from spun down sample and sent frozen.

Transport Instructions

Whole blood should be sent over overnight at ambient temperature. Do not freeze whole blood. Samples for enzyme analysis must arrive to the lab within 24 hours of blood draw.

Cultured fibroblasts can be sent overnight at room temperature.

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

Biochemical Testing, Enzyme Analysis, Individual Enzyme Assays
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