WHAT is NIPT?
Non-Invasive Prenatal Testing (NIPT) is a screening test to detect pregnancies at a higher risk for a specific group of chromosome conditions including Down syndrome (trisomy 21), trisomy 13, trisomy 18 or sex chromosome differences. The test involves a blood draw from the mother to measure small amounts of the baby’s DNA in her blood.
WHAT are the most common chromosome conditions screened for via NIPT?
Humans have 23 pairs of chromosomes, which are packages of DNA that carry our genetic information. A trisomy is a condition that occurs when there are three copies of a particular chromosome instead of the expected two.
- Trisomy 21, also known as Down syndrome, is due to an extra copy of chromosome 21 and is the most common trisomy at the time of birth. Down syndrome is associated with mild to moderate intellectual disabilities and sometimes digestive problems or heart problems. Most infants born with Down syndrome will survive well into adulthood. It is estimated that trisomy 21 is present in one out of every 700 newborns.
- Trisomy 18 is due to an extra copy of chromosome 18. Trisomy 18 is associated with a high rate of miscarriage. Infants born with trisomy 18 often have congenital heart defects as well as various other medical conditions, shortening their lifespan. It is estimated that trisomy 18 is present in approximately one out of every 5,000 newborns.
- Trisomy 13 is due to an extra copy of chromosome 13. Trisomy 13 is associated with a high rate of miscarriage. Infants born with trisomy 13 usually have severe congenital heart defects and other medical conditions. Survival beyond the first year is rare. It is estimated that trisomy 13 is present in approximately one out of every 16,000 newborns.
- There can also be chromosome conditions caused by differences in the number of sex chromosomes. These conditions are typically milder with findings that may include learning disabilities and infertility.
WHEN is NIPT offered and for whom?
NIPT is available at 10 weeks of pregnancy or after. NIPT has been recommended by national societies for all women at high risk to have a baby affected with a chromosome trisomy. Additionally, NIPT has now become available as a screening test for any pregnant patient as it has been proven to be a superior test to traditional screening for the common chromosome trisomies.
WHAT does it mean if I have a high risk result from my NIPT test?
A high risk result from an NIPT does NOT always mean that your baby has a chromosome condition. The information provided by NIPT is a risk assessment; and therefore an abnormal result means that your pregnancy is at a high risk for a chromosome condition. To confirm a diagnosis of any chromosome condition, additional diagnostic testing must be performed, such as Chorionic Villus Sampling (CVS) or an Amniocentesis. These tests can be discussed with you by your genetic counselor or healthcare provider.
WHY might a patient want NIPT?
A patient may be interested in learning their risk for a chromosome condition in their pregnancy for preparation purposes, or to ensure that they get proper management for their pregnancy. However, if the pregnancy is confirmed to be affected with a chromosome condition, the presence of an extra chromosome or the absence of a chromosome cannot be changed for the baby. Some medical management decisions may be made differently by patients or their providers if they knew their baby had a chromosome condition.
HOW do I get Non-Invasive Prenatal Testing?
If you are interested in NIPT you should discuss this with your healthcare provider. In some instances they will ask you to speak with a genetic counselor in advance of the test, or in the event your results suggest that you are at high risk for a chromosome condition in your pregnancy, to further discuss additional testing options.
WHAT in included in a prenatal genetic counseling session?
An appointment with a genetic counselor prior to or after your NIPT testing is often recommended.
A genetic counselor will:
- Provide an evaluation of your risk for chromosome conditions or other genetic conditions in the pregnancy based on personal and family medical history;
- Discuss available screening/testing options to better clarify your risks, including the benefits, limitations, and possible outcomes;
- Communicate directly with your care providers regarding your preferences for screening/ testing and your results to ensure coordinated care.
TO SCHEDULE A PRENATAL GENETIC COUNSELING APPOINTMENT. . .
Locate a prenatal genetic counselor from Minnesota at mygenepool.org or ask your doctor for a referral. Genetic counselors from Minnesota and elsewhere can also be located by using the ‘find a counselor’ feature at nsgc.org.