First Trimester United Screening Approach:
The First Trimester United Screening Approach is a test used by Insight Medical Genetics that provides patient-specific risk assessments for chromosome abnormalities in a pregnancy. These include Down syndrome, trisomy 18, trisomy 13, Turner syndrome, triploidy, and sex chromosome abnormalities (XXX, XXY, XYY). It also provides an assessment of overall risk for any chromosome abnormality in the pregnancy.
The First Trimester United Screening Approach uses information obtained from a blood sample as well as a specialized ultrasound. The blood test is done at approximately 10-11 weeks gestation and measures two proteins, called free beta hCG and PAPP-A, that circulate in a pregnant woman's bloodstream. Then, at 12-13 weeks gestation, an ultrasound is done to look for specific ultrasound markers that can be seen in the first trimester, particularly the amount of fluid behind the neck of a fetus, called the nuchal translucency.
The First Trimester United Screening Approach is offered to women who will be under the age of 35 at the time of delivery or for women over the age of 35 who are not eligible for cell-free DNA testing.
Cell-Free DNA Testing (cfDNA):
Insight Medical Genetics offers the newest screening option for chromosome abnormalities in a pregnancy, a blood test called cell-free DNA testing (cfDNA). This test measures the presence of fetal DNA circulating in a pregnant woman's blood. At this time, cfDNA is able to screen with high detection rates for the most common chromosome abnormalities, including Down syndrome, trisomy 18, trisomy 13, as well as sex chromosome abnormalities. It can also determine fetal gender.
cfDNA testing is offered to women who are considered to be at an increased risk for a fetal chromosome abnormality. Indications for cfDNA testing include being over the age of 35 at the time of delivery, a positive first trimester screening result, identification of certain abnormalities identified by ultrasound, or a history of a previous pregnancy with a chromosome abnormality.
Carrier Screening:
Carrier screening is a blood test that is performed to determine if you or your partner carry certain changes in your genes (called “mutations”) that could cause an inherited disorder to be passed on to your children. Having a family member with an inherited genetic condition or having a family member who is a known carrier for a genetic syndrome increases the likelihood that a person is a carrier; however, it is important to remember that these conditions usually occur in families with no previous history of the condition. Additionally, certain genetic disorders are more common in specific ethnic groups. The conditions included in carrier screening tests other than fragile X syndrome are inherited in an “autosomal recessive” manner. This means that if both partners, or donors, are carriers for the same condition, there is a 25% chance that the pregnancy with inherit the condition.
Insight Medical Genetics offers carrier screening for cystic fibrosis, spinal muscular atrophy, and fragile X syndrome for all couples, regardless of age, family history, or ethnic background. If a patient or a patient’s partner has European Jewish ancestry we will also discuss the option of the Ashkenazi Jewish carrier screening panel. Similarly, if there is history of French Canadian ancestry, we will discuss the option of carrier screening for Tay-Sachs disease. Your genetic counselor or physician may also offer other carrier screening tests based on your ethnic background or reported family history. For couples who are interested in more extensive carrier screening tests, we offer options for extended carrier screening panels as well.
Prenatal Diagnostic Testing:
Chorionic villus sampling (CVS) and amniocentesis are available as an option for at-risk couples, and are performed in conjunction with The Center for Genetic Medicine at Northwestern University. While prenatal diagnostic testing is available to all women, it is an especially appropriate option to consider for women at higher risk for chromosome conditions, such as women who are 35 and older or who have had a previous pregnancy with a chromosome condition. Your doctor may also recommend diagnostic testing if you have had a high risk result on one of the screening tests, or if a birth defect has been seen on ultrasound.
CVS:
Chorionic villus sampling (CVS) is typically performed between 10 and 14 weeks of pregnancy, and involves removing a small amount of placental tissue, called chorionic villi, which is then tested for chromosome abnormalities. The placental tissue that is removed is expected to have the same genetic makeup as the developing fetus, and therefore allows us to observe the genetic makeup of the fetus.
Amnio:
Amniocentesis, an option for prenatal diagnosis, is typically performed during the 15th week of pregnancy or later and involves removing a small amount of amniotic fluid from the amniotic sac. In the amniotic fluid, there are fetal cells called amniocytes. Amniocytes are cells that originated from the fetus and can be tested for chromosome abnormalities, and therefore sampling the amniotic fluid gives us access to the genetic makeup of the fetus.
Genetic Counseling:
Genetic counseling is provided for all individuals having prenatal screening and/or diagnostic testing performed through our office. We also provide genetic consultations for couples with a history of recurrent miscarriage, parents of children with birth defects, couples at risk for a child with an inherited condition, and individuals at risk for familial cancers and other hereditary diseases.
Teratogen Counseling:
Insight Medical Genetics is the home for the Illinois Teratogen Information Service, a free statewide service that provides information regarding all types of exposures during pregnancy.