Learn about birth defects caused by chromosomal disorders and tests used to identify them offered by the Department of Obstetrics & Gynecology at Massachusetts General Hospital.
Prenatal diagnosis means finding birth defects during pregnancy. There are three different kinds of birth defects and different tests to identify them.
Several different tests are available. This information, along with consultation with your health care provider, will help you choose which tests you want. Most likely all of the results will be normal, and you will be reassured.
Frequently Asked Questions About Genetic Syndromes
What are genetic syndromes?
The blueprint for the human body is 'written' in DNA. The 'words' are called genes. A mistake in the DNA can change how a gene works. This can result in a pattern of abnormalities called a genetic syndrome.
How can you tell if my baby will have a genetic syndrome?
We offer carrier screening for certain common diseases, looking for a copy of a defective gene in apparently healthy people. We also take a careful family history of both parents to see if we can find any other problems.
What syndromes can you find using carrier screening?
- Cystic fibrosis is a disease that mostly affects the lungs, but can also cause problems with digestion. It can be mild to very severe
- Spinal Muscular Atrophy (SMA) causes muscle weakness that gets worse over time
- Fragile X syndrome can result in intellectual disability (in the past this was called mental retardation). Boys are more severely affected than girls. Also, women who are carriers are at risk for certain problems themselves
There are some disorders that are more common in certain ethnic groups.
- Anemias such as sickle cell disease and thalassemia are more common in people from the Mediterranean, Middle East, Africa including African-Americans and the Caribbean, other Hispanics and Asians
- Ashkenazi Jewish Diseases are a group of diseases seen more commonly in people of eastern European Jewish descent
- Tay-Sachs disease is more common in French Canadians
Does negative carrier screening mean my baby will not have a genetic syndrome?
No. There are many genetic syndromes that don’t have screening tests. Also, a negative screening test reduces - but does not eliminate - the chance that the baby will have that syndrome.
It is also important to know that when we do find a syndrome, it is often difficult to predict how severely the baby will be affected.
How does carrier screening take place?
Usually the first step is a blood sample from the mother. If she is found to be a carrier of one of these syndromes, the next step is to see if the father is also a carrier for the same syndrome. Chances are he is not. But if he is, we can see if the fetus is affected, using either a CVS or an amniocentesis, which are described below.
For Fragile X syndrome, we do not need to draw blood from the father.
What if I have more questions about genetic syndromes?
You can speak to a genetic counselor at any point in this process to help you learn more about your particular situation so you can make the best choice about what tests to get.
Are these genetic tests covered by my insurance?
Everyone’s insurance coverage is different, and not all genetic tests are covered by all insurance companies. Contact your insurance company to see which tests are covered and if there are any out-of-pocket costs. This information may help you decide which tests you want done. Our office can help by giving you the correct test code when calling your insurance.
Do I have to have these tests?
No. Many women choose to have screening only for certain genetic syndromes, or none at all.
Making a Decision
Before you agree to have a test, you should think about what you will do with the information. Many couples would not have a CVS or amniocentesis under any circumstances. They would not end the pregnancy if the baby is affected, and/or they do not accept the risk of miscarriage from CVS or amnio. These couples might not want to have screening tests.
Think about these questions before deciding to have any form of genetic testing:
- Is this information I want to know before delivery?
- How do I feel about ending the pregnancy?
- How do I feel about raising a child with a disorder?
- What impact will this have on my family?
- Who will care for an adult with special needs when I am no longer able?
- How do I feel about miscarriage?
- If I decide not to have testing, will I worry about this until the baby is born?
Remember that all of these tests are optional and entirely your choice. Discuss your options with your provider or a genetic counselor.
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OB/GYN at Mass General
The Department of Obstetrics & Gynecology at Mass General consistently ranks among the best women's health care providers in the country, offering innovative treatments from leading experts in obstetrics, gynecology, infertility, cancer, and urogynecology. Learn more about our department.