By Yolanda Smith, BPharm
Tay-Sachs is a genetic disease that can be prevented through certain methods of mate selection, antenatal screening and pre-implantation genetic diagnosis. These techniques can be utilised to reduce the likelihood of individuals being born with Tay-Sachs disease, as a way of prevention.
Tay-Sachs disease is inherited in an autosomal recessive pattern, which requires both parents to carry a gene mutation of the disease in order for a child to have a possibility of being affected.
This knowledge has been used in Orthodox Jewish circles to assist couples in choosing a suitable mate to ensure their children will not be affected by the condition. An organisation called Dor Yeshorim runs an anonymous screening program for the disease with blood tests of adolescents in high school.
Each individual is given an identification number, which can be quoted to hotline when planning to start a family with a partner. If both partners are carriers of the disease, they will receive “incompatible” results and advised to find alternative partners. This identification system is designed to minimise any stigma that may result from individuals being categorised as a genetic carrier.
This method of prevention has been effective among specific populations, although it is not clear if it would work in general population groups, particularly those that may not consent to widespread genetic testing. However, some experts have taken an interest in a similar technique to extend this idea as a public health method of prevention.
If both parents that are expecting a child are known to be genetic carriers of Tay-Sachs disease, there is a 25% chance that any children will be affected by the condition. Antenatal testing can be used in this instance to determine in the foetus is likely to be affected by the disease.
This can be carried out with chorionic villus sampling (CVS) from weeks 10 to 14 of the pregnancy, with a cell sample from the placenta that is tested for evidence of the disease. Alternatively, amniocentesis is a diagnostic test that involves a sample of the amniotic fluid between weeks 15 and 20 of the pregnancy that is tested for the disease.
The results of these tests can diagnose a foetus with Tay-Sachs disease with sufficient accuracy to allow expectant parents to decide whether they would like to continue the pregnancy to full-term. Many couples choose to terminate the pregnancy, preventing the disease and the related complication that would arise with it. However, this decision raises certain ethical issues and can be particularly difficult for both the family and health practitioners involved.
Pre-implantation Genetic Diagnosis
Couples that are both known genetic carriers of Tay-Sachs disease can opt for pre-implantation genetic diagnosis to avoid conceiving a child that will be affected by the disease.
Similarly to in-vitro fertilization (IVF), this technique involves harvesting of the woman’s ova, which are fertilized by the father’s sperm in a laboratory. The embryos can then be tested for the Tay-Sachs disease and only those that are unaffected will be implanted into the woman’s uterus for the pregnancy to go ahead. This technique is also used for other genetic diseases, such as cystic fibrosis and sickle cell anaemia.
However, this method is largely limited by the high expense of the procedure. It is not currently covered by public health systems and it is often beyond the financial means of couples that would benefit.
Last Updated: Sep 28, 2015