Tay Sachs Disease
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 that is common in individuals of French Canadian descent. In addition, the two psuedodeficiency alleles (p.R247W and p.R249W) are tested. These two variants, while benign, will give a false positive screen on the enzyme assay present. 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.
Full gene sequencing is available for reproductive partners of known mutation carriers. Prenatal diagnosis is also available. Prior to ordering prenatal testing, please contact our laboratory at 212-241-7518 to discuss.
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.
Post-natal: One 5-10 mL tube of anticoagulated blood in EDTA (lavender top) or two 5-10 mL tubes of anticoagulated blood in ACD (yellow top). Alternatively, three 5-10 mL tubes of anticoagulated blood in EDTA (lavender top) are also acceptable.
Prenatal: Contact laboratory for prenatal, parental and control specimen requirements for molecular and biochemical analyses.
Shipping: Ship at room temperature.
Turnaround Time: 10-14 days
CPT Codes: 81255, 80500, 83080x4, 82657x4, 84155 (includes enzyme)
Consent and requisition forms: Carrier Screening Requisition and Consent [PDF]
Additional information: Expanded Ashkenazi Jewish Carrier Screening brochure [PDF]
Related Tests: Ashkenazi Jewish Carrier Screening Panel