Prenatal Diagnosis

Prenatal diagnosis uses a variety of techniques to determine the health of an unborn fetus. Chorionic villus sampling (CVS) and amniocentesis determine if a fetus is affected by Tay-Sachs or an allied disease.

chorionic villus sampling (CVS) - procedure used for prenatal diagnosis, which involves insertion of a needle through the abdomen into fingerlike projections of the placenta which are called chorionic villi. This procedure is also performed using ultrasound guidance, and testing can be performed with the tissue obtained. Depending upon the location of the placenta, the tissue may be obtained transvaginally rather than abdominally, by inserting a catheter through the cervix and into the uterus. CVS is usually performed at 10 to 12 weeks of pregnancy.

amniocentesis - procedure used for prenatal diagnosis, which involves insertion of a needle through the abdomen into the amniotic fluid. This procedure is performed using ultrasound guidance, and allows the physician to obtain a small amount of amniotic fluid which can then be used for testing.
Amniocentesis is usually performed between 16 and 18 weeks of pregnancy, but some centers offer “early amnio” at 14 weeks of pregnancy.

Each procedure has inherent risk of miscarriage; please discuss the those risks with your obstetrician.

Prenatal Testing: Limited Availability for Carrier Couples

If you have a child or family member affected by a lysosomal storage disease (LSD) such as Tay-Sachs, Sandhoff, Niemann-Pick or another of the allied diseases and are currently pregnant or considering a future pregnancy, please conatct your genetic counselor or geneticist immediately.

As of August 2005, the availability of prenatal testing for many LSDs has changed. Fewer laboratories now offer prenatal testing. For some diseases, prenatal testing is no longer available in the United States. Other diseases may require new tests and retesting for parents, affected siblings, and other family members prior to prenatal testing. In these situations, testing will most likely take longer than it did in the past. Testring during prenancy is stressful, so we encourage you to contact your healthcare providers early to discuss your plans.

Do not wait until you are pregnant to ask about prenatal testing! Be proactive and call your genetic counselor, geneticist, and/or NTSAD for an update on prenatal testing. To find a genetic counselor in your area, conatct the National Society of Genetic Counselors or check their website at www.nsgc.org, or speak with your physician for a referral. You should also address this issue with your ob/gyn or other healthcare professional so they are aware of changes in prenatal testing availablity for carrier couples of lysosomal disorders.

NTSAD is working with laboratories and the Office of Rare Diseases at NIH to address the LSD prenatal testing issue, and it is expected that testing availablity willl continue to change over the next few years. Through Lifeline, E-News and other forms of NTSAD communication, we will keep you updated on developments with this important issue.