Maternity Care Guidelines: Screening for Tay Sachs Carriers

Current MCC Guideline (1998):

Tay Sachs disease testing in Ashkenazi Jews by hexosaminidase-A in serum (men, non-pregnant women) or WBCs (pregnant women).
in plain font
listed under "Investigations" suggested for early pregnancy

Literature Search:
The MeSH heading "Tay Sachs screening" was searched on pubmed for the years 1998 to present.

Summary of Evidence:
Tay-Sachs disease (TSD) is a lysosomal storage disease causing severe progressive neurological symptoms that primarily affects the Ashkenazi (Eastern European) jewish population.¹ It is a recessive disorder with a carrier frequency in the Ashkenazi Jewish population of between 1/20 and 1/30.² It has been shown that people of French Canadian (particularly Gaspé region) and Cajun descent also have a greater carrier frequency than the general population.³

Tay-Sachs disease is characterized by a deficiency in the hexoaminidase A enzyme and exists in two forms: the infantile and juvenile forms. Children stricken with the infantile form die by age 2 to 3 years, while children with juvenile form die by age 15.¹ Due to the mortality and emotional suffering for the parents associated with Tay-Sachs disease, carrier testing for TSD has been carried out for 20 years and has resulted in a 90% decrease in the incidence of TSD.³ If testing is done in women who are pregnant or using oral contraceptives, leukocyte testing must be used instead of serum testing. Prenatal testing for TSD can also be done by measuring hexosaminidase activity in samples obtained by amniocentesis or chorionic villus sampling.³

Recommendations of Others:
The Canadian Task Force on Preventive Health Care gives it a grade A recommendation.⁴

The American College of Obstetricians and Gynecologists recommends screening for TSD before pregnancy of both members of a couple who are Ashkenazi Jews or of French Canadian or Cajun descent or have a family history of TSD. When only one member of a couple is from a high risk group, they should be screened first. Ambiguous tests should be confirmed by molecular analysis for the most common mutations. If both partners are carriers, genetic counseling and prenatal diagnosis should be offered.³

Conclusion:
The new guideline for Tay-Sachs screening on the MCC should be bolded to read:

Tay Sachs disease testing in Ashkenazi Jews by hexoaminidase-A in serum (men, non-pregnant women) or WBCs (pregnant women).
It will be in bold font as there it is a grade A recommendation
Listed under "Investigations" suggested for preconception visit (or alternatively, early pregnancy)

Reviewers:
Amrit Kahlon, (medical student) July 2002
Colleen Kirkham MD, CCFP October 2002

Thank you to Dr. Sylvie Langlois (Department of Medical Genetics, Children's and Women's Health Centre of British Columbia) and Dr. Hilary Vallance (Biochemical Genetics lab, Department of Pathology, Children's and Women's Health Centre of British Columbia) for their helpful comments.

10/7/2003

¹Hansis C, Grifo J. Tay-Sachs Disease and Preimplantation Genetic Diagnosis. Advances in genetics 2001; 44: 311-15.

²Shabat, S. Economics of screening programs for Tay-Sachs disease. Health Policy 1999; 47(2): 183-4.

³Kaback MM. Population-based genetic screening for reproductive counseling: the Tay-Sachs disease model. European Journal of Pediatrics 2000; 159[Suppl 3]: S192-95.

⁴Canadian Task Force on Preventive Health Care. http://www.ctfphc.org

Further Reading:

Kaplan F. Tay-Sachs Disease Carrier Screening: A Model for Prevention of Genetic Disease. Genetic Testing 1998; 2(4): 271-92.

D'Souza G et al. Tay-Sachs Disease Carrier Screening: A 21-Year Experience. Genetic Testing 2000; 4(3): 257-63.