The tests can be performed on blood, urine, saliva, body tissues, bone, or hair.
Genetic testing can also be used in legal investigations.
There are even direct-to-consumer tests able to trace your ancestry.
Illustration by Cindy Chung, Verywell
How Genetic Tests Work
Nearly every cell in your body containsDNA, genes, and chromosomes.
Types of Genetic Tests
Genetic tests have far-ranging applications in medical and non-medical prefs.
Currently Available Tests
The number of genetic tests available to diagnose disease is increasing each year.
Prenatal Risks
Prenatal genetic testing is commonly performed on maternal blood.
One example is the cell-free fetal DNA (cfDNA) test performed after the 10th week of pregnancy.
Genetic testing can also be performed on amniotic fluid obtained throughamniocentesis.
Side effects may include cramping, localized pain at the puncture site, and accidental bladder perforation.
Amniocentesis carries a one-in-400 risk of miscarriage.
CVS can be used to screen for the same congenital conditions with the exception of neural tube defects.
Side effects may include spotting, cramping, or infection.
The uncertainty can cause stress about your future and/or your ability to obtain health or life insurance when needed.
Efforts are being made to address some of these concerns.
This includes your “right not to know” if any unintended findings are uncovered.
There is no wrong or right answer in either regard; there is only personal choice.
Before the Test
A genetic test does not require much preparation on your part.
The only exception may be prenatal tests, which sometimes require food and/or fluid restrictions.
With the exception of direct-to-consumer ancestry kits, most genetic tests will involve some level of pre-test counseling.
Biopsies may take longer, particularly those involving bone marrow or the colon.
Prenatal screening is performed as an in-office procedure.
You may ask your provider to verify this to ensure the lab meets these strict standards.
For prenatal screening or a biopsy, you may be asked to partially or fully undress.
If so, leave any valuables at home.
A hospital gown will be provided if needed.
Food and Drink
Generally speaking, there are no food or drink restrictions for a genetic test.
Eating, drinking, or taking medications will not affect the outcome of the test.
Speak with your healthcare provider to ensure you adhere to the appropriate dietary guidelines.
What to Bring
Be sure to bring your ID and health insurance card to your appointment.
Most genetic tests require insurance pre-authorization.
By and large, genetic tests are approved if the test helps prevent disease progression or improve treatment outcomes.
With that being said,copay and coinsurancecosts can often be prohibitive.
Direct-to-consumer ancestry tests are priced between $50 and $200, and they are not covered by insurance.
The counseling can vary based on the aims of the procedure.
Throughout the Testing
Once the counseling is complete, the sample will be obtained for testing.
Tissue samples may also be obtained as an adjunct to other direct diagnostic procedures, such as acolonoscopyorendoscopy.
In that case, someone will need to drive you home.
These can be signs of an infection, requiring prompt treatment.
Symptoms tend to be mild and usually resolve within a day.
The sample then undergoes a process called DNA sequencing to identify the exact ATCG coding in the DNA.
The result is run through a computer to compare the sequence to that of the human genome reference.
Commercial labs tend to be faster than institutional or research labs.
For the most part, single-gene tests will deliver a positive, negative, or ambiguous result.
U.S. National Library of Medicine.What are the risks and limitations of genetic testing?Genetics Home Reference.
U.S. National Library of Medicine.What is genetic discrimination?Genetics Home Reference.
Ambry Genetics.How are direct-to-consumer and medical-grade genetic tests different?
