ADVANCED TESTING OPTIONS
Here is a series of helpful videos that outlines the different testing options available.
Screening:
Non-Invasive Prenatal Testing (NIPT):
Purpose: NIPT screens for common chromosomal abnormalities, such as Down syndrome (Trisomy 21), Trisomy 18, Trisomy 13, and sex chromosomes (X and Y).
Procedure:
A blood sample is taken from the pregnant individual.
Cell-free fetal DNA in the maternal blood is analyzed to assess the risk of chromosomal abnormalities.
Of note, this test can also typically be used to determine the sex of the fetus, if you wish to find out.
Timing: Usually performed after 10 weeks of pregnancy.
Diagnostic Tests
Expanded Carrier Screening:
Purpose: Identifies whether parents carry genetic mutations that could be passed on to the baby, leading to specific genetic disorders.
Procedure:
Blood or saliva samples are collected from one or both parents.
You might consider testing for one partner first (for example the pregnant person if already pregnant) and if that person is negative for all the genetic conditions tested, then the other partner might forgo testing. Or, you might prefer to simultaneously proceed with testing for both individuals.
The samples are analyzed to detect carrier status for certain genetic conditions. Some conditions tested for are:
Cystic fibrosis, Tay-Sachs disease, sickle cell disease, spinal muscular atrophy, and fragile X syndrome.
Other Conditions: Canavan disease, Niemann-Pick disease, Gaucher disease, Duchenne/Becker muscular dystrophy, and many others.
Timing: Can be done before or during pregnancy.
3. Chorionic Villus Sampling (CVS):
Purpose: Diagnoses chromosomal disorders and some genetic conditions by analyzing a sample of the placenta (chorionic villi).
Procedure:
A small sample of placental tissue is taken through the cervix or the abdominal wall.
The fetal cells from the sample are analyzed for genetic abnormalities which could include:
Chromosomal abnormalities: such as Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18), and Patau syndrome (Trisomy 13).
Other genetic disorders: including cystic fibrosis, sickle cell disease, and Tay-Sachs disease.
Timing: Typically performed between 10 and 13 weeks of pregnancy.
4. Amniocentesis:
Purpose: Diagnoses chromosomal disorders and certain genetic conditions by analyzing a sample of the amniotic fluid.
Procedure:
A thin needle is inserted through the abdominal wall into the amniotic sac to collect a small amount of amniotic fluid.
The fetal cells from the fluid are analyzed for genetic abnormalities including:
Chromosomal abnormalities: Such as Down syndrome, Edwards syndrome, and Patau syndrome.
Genetic disorders: Such as cystic fibrosis, sickle cell anemia, and muscular dystrophy.
Neural tube defects: Such as spina bifida and anencephaly.
Fetal lung maturity: To determine if the baby's lungs are mature enough for birth.
Infections: In some cases, amniocentesis can detect infections in the amniotic fluid.
Timing: Usually performed between 15 and 20 weeks of pregnancy.
5. Expanded Carrier Screening:
Purpose: Screens for a broader range of genetic conditions, including those more common in specific ethnic groups.
Procedure:
Blood or saliva samples are collected from one or both parents.
The samples are analyzed for carrier status for a wide range of genetic conditions.
Timing: Can be done before or during pregnancy.
6. Whole Genome Sequencing (WGS) and Whole Exome Sequencing (WES):
Purpose: Provides a comprehensive analysis of the entire genome (WGS) or specific protein-coding regions (WES) to identify a wide range of genetic conditions.
Procedure:
Involves sequencing the complete genome (WGS) or exome (WES) from a DNA sample.
Timing:
Can be performed at various stages of pregnancy, may be considered after an ultrasound identifies one or more major physical abnormalities of the fetus that could be due to a genetic disorder
Important Considerations:
Consultation with a Genetic Counselor: Before undergoing advanced genetic testing, it's recommended to consult with a genetic counselor. They can provide information about the tests, help assess the need for testing, and explain the potential outcomes.
Informed Decision-Making: Individuals should fully understand the benefits, limitations, and potential emotional implications of genetic testing before making decisions.
Risk Assessment: Some tests are more invasive and carry a small risk of miscarriage. The level of invasiveness may be a consideration in the decision-making process.
Cost and Insurance Coverage: The cost of advanced genetic testing can vary, and insurance coverage should be considered. If you are of “advanced maternal age” (35+) generally, more genetic testing is covered by private insurance.
Sources: American College of Obstetricians and Gynecologists (ACOG), NIH
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