Carrier Testing

Cystic fibrosis, Tay-Sachs disease, Canavan disease, Gaucher disease, Bloom syndrome, Fanconi anemia, Familial dysautonomia, Niemann-Pick disease, Mucolipidosis IV (MLIV), Familial Hyperinsulinism, maple syrup urine disease, glycogen storage disease Ia, and Fragile X syndrome are hereditary disorders that are more common in certain ethnic groups. In the past, people learned about their risk for having affected children only after the child was born. Through genetic testing, it is possible to identify people whose children may be at increased risk. At New York University School of Medicine, genetic testing is offered for all of these conditions.

Click here to view a video describing carrier testing for diseases common in Ashkenazi Jews.

What causes genetic disease?

For most of the traits in our bodies, we have two genes, one inherited from the mother and one from the father. As the result of a change in the gene (mutation), it may not work in the proper way. Some diseases occur when a person has a change in only one gene. Other diseases (called "recessive") occur when both genes have changed.

What is a carrier?

A carrier is a person who has a change in one of the genes for a recessive disease. Because two changes are required to produce the disease, the person remains well and unaware of his or her carrier status. When two carriers have a child, the child has a 25% chance for being normal. When a carrier has a child with a person who is not a carrier, the child is not at risk for the disease. Fragile X is an X-linked disorder. A carrier woman is at increased risk of having an affected child.

How are genetic tests used to identify carriers?

There are two ways that carrier testing is done. One way is by direct analysis of the genes. The genes are extracted from blood cells. The genes are tested for mutations. The second way is to test for the amount or activity of a gene product that normally prevents disease. Affected individuals have little, if any, of the gene product. Carriers have a 50% reduction in the gene product. The choice of test depends on its ability to detect as many carriers as possible.

How do carriers use genetic information?

When carriers decide to have children, the disease status of the baby can be learned before birth by using prenatal diagnosis. Prenatal diagnosis involves collecting a small sample of placenta between 10 to 12 weeks of pregnancy or a sample of the fluid that bathes the baby between 14 to 20 weeks of pregnancy. (The length of a pregnancy is usually 40 weeks.) Genetic testing is performed on these samples to learn whether the baby has the disease, is a carrier like the parents, or is not a carrier. Sometimes carriers may decide not to have children with other carriers.

Is genetic testing accurate?

The tests cannot detect all carriers/mutations. Even negative results are reported as likelihood for being a carrier. There is a small chance that an error may occur, despite the fact that the testing laboratory uses procedures to assure a high level of quality. In rare instances a result cannot be determined and it may be necessary to obtain another sample. This testing will be performed at no additional cost.

How will I learn my test results?

The results of carrier testing are usually available within two to three weeks from when the specimen was collected and if you are found to be a carrier, a genetic counselor will call you. Your test results will be sent to your physician. If you want to discuss your test result with a genetic counselor, you may do so at any time.

Is genetic testing reimbursable?

Yes, but you should check with your insurance first.

Confidentiality of test results

The test results are your confidential information. They will not be disclosed to others, (including your partner, your insurance carrier, or any other physician who was the physician who ordered the test for you) without your prior consent.

Click here to see the genetic disease chart

If you have any questions about any of this information or would like to schedule an appointment, please feel free to contact us.

Human Genetics Program
550 First Avenue, Room MSB 136,
New York, New York 10016
Telephone: (212)263-5746
Fax: (212)263-7590