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Genetic Carrier Testing

Carrier testing determines if a couple is at increased risk of having a baby with an inherited genetic condition. The following details the more common carrier testing offered to pregnant women. Your clinician evaluates your family history to determine if additional carrier testing should be considered.

  • Ashkenazi Jewish Carrier

    There are a group of rare disorders that occur more often in people of Eastern European (Ashkenazi) Jewish heritage than in the general population. These tests are recommended if one or both parents are carriers Even though most of these diseases are severe and life-limiting, some can be treated to reduce symptoms and prolong life. Some of these diseases can be found during pregnancy through chorionic villus sampling (CVS) or amniocentesis.

  • Fragile X
    Fragile X syndrome is found among all ethnic backgrounds and racial groups. Approximately 1 in 260 women in the general population are carriers of the abnormal gene that causes Fragile X syndrome. Women of any age can have a child affected with fragile X syndrome, whether or not their previous children are healthy.  Fragile X syndrome is the most common cause of inherited mental impairment such as mental retardation, autism, developmental or learning delays, and is the most commonly known cause of autism or “autistic-like” behaviors. 

    Fragile X can be passed on by individuals who have no apparent signs of this genetic condition. In some families, a number of family members appear to be affected, whereas in other families a newly diagnosed individual may be the first family member to exhibit symptoms.

    A sample of the mother’s blood will be tested to determine if she carries the gene responsible for Fragile x syndrome.  If tests results indicate you are a Fragile X carrier, your clinician will recommend further prenatal diagnostic testing such as chorionic villi sampling or amniocentesis.

  • Hereditary Blood Disorders

    Blood disorders affect oxygen levels in the blood stream, such as sickle cell anemia and thallasemia, or clotting such as hemophilia.  Some of these disorders are common in ethnic populations.  A simple blood test can determine if you carry the gene for these diseases.

  • Tay-Sachs Disease

    Tay-Sachs disease is a hereditary illness in children causing central nervous system degeneration – this disease progresses through the early years of childhood and results in untimely death. While prenatal diagnosis can be performed, it is best to know whether or not this is an issue for you, before you get pregnant. Tay-Sachs screening is routinely offered to those with Eastern European Jewish ancestry, among whom the carrier rate is 1 in 27. Since the carrier rate is 1 in 200 in other individuals, your doctor might request such a screening no matter what your heritage.

  • Cystic Fibrosis

    Cystic Fibrosis (CF) is a genetic (inherited) disease that affects breathing and digestion. It is caused by an abnormal gene that makes the body produce thick mucus in the lungs. This mucus promotes infections that often are life threatening. In the pancreas, similar thick secretions can lead to serious problems with food absorption.

    Screening for CF is done by a blood or saliva test. Both parents will be tested and the results identify if either parent carries the abnormal gene that causes CF. The test can help determine increased risk for having a child with CF; if only one parent is a CF carrier, none of the children will have CF, though there is a 50-50 chance that each child will be a symptomless carrier.

    Approximately 1 in 30 Americans is a symptomless carrier. Risk is increased if you're of Caucasian background with a 1 in 29 chance of carrying the gene, compared to 1 in 46 for people of Latino background, 1 in 65 for African-Americans, and 1 in 90 for Asian-Americans.

    If results show that both parents are CF carriers, your provider can test the baby in utero. If the baby has CF, parents can take time before delivery to learn more about the disease and find appropriate specialists. The American College of Obstetricians and Gynecologists (ACOG) recommends that health care providers make the CF carrier screening test available to all couples.

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