Tay-Sachs Disease

Test Description:
Tay-Sachs disease (TSD) is a recessively inherited neurodegenerative disorder caused by a deficiency of beta-hexosaminidase A that leads to a pathological accumulation of GM2 ganglioside. Features include progressive loss of coordination, seizures, difficulty swallowing and poor pulmonary function. Affected individuals eventually become blind, severely mentally retarded, paralyzed and unaware of their surroundings. Onset is typical at approximately 6 months of age, and average life expectancy is 3-5 years. TSD is most prevalent among Ashkenazi Jews with the carrier frequency estimated to be 1 in 27. Targeted mutation analysis is performed in conjunction with enzyme analysis for three different mutations in the HEXA gene [c.1274_1277dupTATC (1278+TATC), c.1421+1G>C (IVS12+1G>C), p.G269S] which are common in this population. We also test for c.1073+1G>A (IVS9+1G>A), which is a recurrent mutation in non-Jews and the g.2644_10588del (del7.6kb) mutation common in individuals of French Canadian descent. In addition, two benign changes (p.R247W and p.R249W, known as “pseudodeficiency alleles”) which will give a false positive screen on the enzyme assay are tested. The American College of Obstetricians and Gynecologists and the American College of Medical Genetics recommend that carrier screening for TSD be offered to individuals of Eastern European (Ashkenazi) Jewish, French Canadian and/or Cajun ancestry before/during pregnancy.

References:
1. Triggs-Raine, B.L. Akerman, B.R., Clarke, J.T.R., and Gravel R.A. Sequence of DNA flanking the exons of the HEXA gene, and identification of mutations in Tay-Sachs disease. Am. J. Hum. Genet. 49:1041-1054, 1991.
2. Akerman, B.R., Natowicz, M.R., Kabak, M.M. Loyer, M., Campeua E. and Gravel R.A. Novel mutations and DNA-based screening in non-Jewish carriers of Tay-Sachs disease. Am. J. Hum. Genet. 60:1099-1106, 1997. 2. Scott, S.A., Edelmann, L., Liu, L., Luo, M., Desnick, R.J. and Kornreich, R. Experience with carrier screening and prenatal diagnosis for sixteen Ashkenazi Jewish Genetic Diseases. Hum. Mutat. 31:1-11, 2010.

Specimen Requirements:
Three 5-10 ml tubes of anticoagulated blood. The preferred anticoagulant is EDTA (lavendar top tubes), ACD (yellow top) tubes are also accepted.

Shipping: Send at room temperature.

Turnaround Time: 10-14 days

CPT Codes: 83891, 83892x2, 83900, 83901x2, 83912, 83914x2, 83080x2, 80500 (includes enzyme testing)

Consent and Requisition Forms: Carrier Screening Requisition and Consent [PDF]

Additional Information: Jewish Genetic Screening Brochure [PDF]

Related Tests: Ashkenazi Jewish Carrier Test Panel

Prior to ordering prenatal testing, please contact our laboratory at 212-241-7518 to discuss.