ColumbiaDoctors provides expert guidance for patients and families who are interested in genetic testing. Our counselors will help you understand complex information about genetic defects, inform you about your testing choices, and help you make decisions about your reproductive choices that work for you and your family.
You may decide to see a genetic counselor for one of several reasons:
- You, your partner, or a close family member may have an inherited disease
- You have a history of recurrent pregnancy losses or infertility
- You are over 35 years old
- Routine prenatal testing, such as an ultrasound, has revealed an abnormality in your unborn child
- Amniocentesis or Chorionic Villus Sampling (CVS) testing has revealed a genetic disorder in your unborn child
Your appointment with a genetic counselor will involve a thorough look at the medical histories of family members on your side and your partner's side of the family. You will want to come prepared with as much information as possible about your relatives, going as far back as possible. Your counselor will look for and advise you about any inherited disorders that might be passed on to your child. Your counselor will also ask you about your own exposure to toxic substances, history of alcohol and drug use, or medications you or your partner may be taking.
Your genetic counselor will give you information about various tests that can help you determine your risk of giving birth to a child with birth defects or health problems. Some of the tests your counselor may discuss with you are:
Carrier Testing: A small blood or saliva sample is taken and tested to determine whether your children have an increased risk of inherited conditions such as cystic fibrosis or sickle cell disease. Your genetic counselor will go over the results with you if you are found to be a carrier. If you are pregnant with a child and you or your partner is a carrier, you can decide to test the the baby, either through a test that involves taking a sample of placenta at around 11 weeks of pregnancy or through a test that involves an amniotic fluid sample taken between 14 and 20 weeks. Your genetic counselor will explain the tests and their risks and any other information you need to make a decision that works for you and your family.
Screening tests: You may have a two, three, or four-part screening, often called a multiple marker screen. Blood is drawn and analyzed for:
- Alpha-fetoprotein (AFP): A protein released by the fetal liver and found in the mother’s blood. AFP is sometimes called MSAFP (maternal serum AFP). Elevated AFP levels can indicate certain birth defects.
- Human chorionic gonadotropin (hCG): a hormone secreted by the early placental cells. High hCG levels may indicate a fetus with Down syndrome (a chromosomal abnormality that includes mental retardation and distinct physical features).
- Estriol: a hormone produced by the placenta and by the fetal liver and adrenal glands. Low levels may indicate a fetus with Down syndrome.
- Inhibin: a hormone produced by the placenta. High levels of inhibin may indicate a fetus with Down syndrome.
Nuchal translucency screening: An ultrasound test usually performed in the late first trimester. Thickening of the area at the back of the fetal neck may indicate an increased risk for Down syndrome or other chromosomal problems.
Chorionic villus sampling (CVS): A prenatal test that involves taking a sample of some of the placental tissue, which can be tested for chromosomal abnormalities and some other genetic problems.
Amniocentesis: A procedure used to obtain a small sample of the amniotic fluid that surrounds the fetus to diagnose chromosomal disorders and open neural tube defects (ONTDs) such as spina bifida.
Ultrasound: A diagnostic technique that uses high-frequency sound waves to create an image of the internal organs. Many birth defects can be detected with ultrasound.
Preimplantation genetic screening and diagnosis (PGS/PGD): These tests help evaluate an embryo before it is implanted by in vitro fertilization (IVF). Cells are removed from the embryo (biopsy) and tested for potential genetic conditions. PGD tests for single gene diseases that are inherited from one or both of the parents, including sickle cell anemia, Tay Sachs, cystic fibrosis, and Huntington’s disease. PGS tests for chromosomal abnormalities that can cause miscarriage or IVF failure, or a trisomy such as Down syndrome.