Tay-Sachs disease, DNA analysis

Alphabetical Test listing

Tay-Sachs disease, DNA analysis-13555

Tay-Sachs disease, DNA analysis
Hexosaminidase A deficiency

Pre- and postnatal determination of Tay-Sachs disease carrier status; resolution of pseudodeficiency allele status.

EDTA whole blood
7 mL
3 mL

Lavender (EDTA), 10mL

ACD whole blood
Amniotic fluid;Chorionic villus sample (CVS) (submission of maternal blood is required for fetal testing)

Yellow ACD (A or B)


Sterile vial/container





Amniotic fluid - 10 mL (minimum 5mL); CVS - 20 mg (minimum 10 mg)

Yellow ACD (A or B)

Sterile vial/container



  • Frozen specimen
  • Hemolysis
  • Quantity not sufficient for analysis (QNS)
  • Improper container
LabCorp RTP (510404): R-LC
2 X / wk, or as needed
8 - 14 days

Polymerase chain reaction (PCR); primer extension; flow- sorted bead array analysis for five mutations and two pseudodeficiency alleles in the hexosaminidase A gene


An interpretive report will be provided


Tay-Sachs disease is an autosomal recessive lysosomal storage disorder that causes progressive neurological deterioration ranging in severity from forms with infantile onset to those with adult onset. If the individual tested by DNA analysis is not of Ashkenazi Jewish descent, carrier testing by enzyme analysis is strongly recommended. Couples who are both carriers have a one in four risk of having a child with Tay-Sachs disease. DNA test results should be combined with enzyme test results and clinical information for the most accurate interpretation. The mutations tested include: 1278insTATC, G269S, IVS9+1 G>A, 1421+1 G>C, 7.6 kb deletion. Pseudodeficiency alleles tested include: R247W and R249W.

NOTE: The pseudodeficiency mutation, R247W, accounts for 32% of enzyme-defined carriers in the non-Jewish population, while R249W accounts for 4% of pseudodeficiency among Ashkenazi Jews. These mutations affect the enzyme test, but do not affect in vivo function of beta-hexosaminidase A. Carriers of these mutations are not at increased risk to to have children with Tay-Sachs disease.

Result 32632-2