Genetic testing is a minimally invasive medical test that doctors use to identify genetic mutations or variants that can lead to certain diseases or conditions. Doctors use various types of genetic tests for different purposes.
Genetic testing can provide valuable insights into an individual’s genetic makeup. It can potentially identify the risks of various diseases, inherited conditions, and even traits passed down through generations. The information obtained from test results can be crucial for making decisions about health and treatment options.
This article aims to provide an overview of genetic testing, outlining what it is, why it is done, and what individuals can expect before, during, and after the process.
Genetic testing is a term describing medical tests that involve analyzing a person’s DNA, a molecule found in most cells of the body. DNA provides instructions to proteins in the body necessary for normal functioning.
The test can reveal genetic changes — also known as mutations or variants — in a person’s genes, chromosomes, or proteins.
The process typically involves collecting blood, saliva, or tissue samples that doctors send to a laboratory. Genetic testing results can provide key information about susceptibility to disease or can guide treatment.
Medical professionals carry out genetic testing for several reasons. Some of the primary reasons include:
- Diagnosing genetic conditions: It can confirm or rule out genetic disorders in individuals showing symptoms.
- Carrier testing: Couples planning to have children may undergo genetic testing to determine if they carry genes for inherited conditions, such as cystic fibrosis (CF) or sickle cell anemia.
- Predictive and presymptomatic testing: For individuals with a family history of certain conditions, genetic testing can determine the risk of developing diseases, including Huntington’s disease or certain types of cancer.
- Pharmacogenomics: A certain type of genetic testing helps identify how a person’s genetic makeup might affect their response to drugs. This information can help guide personalized treatment plans.
- Prenatal testing: During pregnancy, some genetic tests can screen for conditions like Down syndrome and other chromosomal abnormalities in the developing fetus.
- Newborn screening: In the U.S., doctors carry out newborn screening within the first few days of a baby’s life. It can detect genetic abnormalities, which means an infant can receive a diagnosis earlier and start treatment. Newborn screening is a state-run healthcare initiative, with nearly
four million children undergoing screenings yearly.
Various types exist, as no single genetic test can detect all genetic changes.
A healthcare professional can recommend the most appropriate genetic test for an individual, depending on family history and the specific condition they are assessing for.
Cytogenetic testing
This type of genetic test examines whole chromosomes to identify large-scale genetic changes, such as extra or missing chromosomes. This can help diagnose conditions such as Down syndrome.
Cytogenetic tests can also detect structural abnormalities in chromosomes, such as translocations or deletions, that may have associations with various genetic disorders.
Biochemical testing
Biochemical tests measure the levels or activity of proteins that genes produce. Since genes provide instructions for making proteins, atypical levels of some proteins can indicate a genetic disorder.
These tests can diagnose metabolic disorders, such as phenylketonuria (PKU).
Molecular testing
Molecular genetic testing focuses on identifying small DNA mutations, such as point mutations, insertions, or deletions, that may not be detectable with the tests mentioned above.
It is highly specific. Doctors often use it to diagnose conditions like CF or sickle cell anemia.
Direct-to-consumer genetic tests
Clinical genetic tests differ from direct-to-consumer (DTC) genetic tests.
A healthcare professional uses clinical genetic tests for specific medical reasons, and they are not available for use at home. Individuals can purchase DTC genetic tests online or in stores, often to explore ancestry or other personal traits.
Individuals should not use DTC tests alone to make decisions about treatment or medical care, and they do not replace clinical testing.
While genetic testing provides valuable insights, it comes with some risks, primarily emotional and social, though physical risk is still possible.
Some risks may include:
- unexpected results
- privacy concerns
- inconclusive results
For prenatal testing, such as amniocentesis or chorionic villus sampling (CVS), there is a
Genetic tests involve:
- Consultation: Before testing, people usually meet with a genetic counselor or healthcare professional to discuss the potential risks, benefits, and limitations of the test. This consultation helps individuals make an informed decision about whether to proceed with testing.
- Sample collection: This step involves collecting a sample of blood, saliva, or tissue. Sample collection is often a simple, minimally invasive procedure.
- Waiting for results: After a healthcare professional collects the sample, they send it to a lab for analysis. Depending on the complexity of the test, the wait time for results can vary from a few days to several weeks or months.
- Receiving results: Doctors usually share results during a follow-up appointment and discuss what they could mean for the individual.
The results can be:
- Positive: This indicates a person has changes in the gene, chromosome, or protein of interest. Depending on why it was done, results can:
- confirm a diagnosis
- indicate an increase in risk for a particular condition
- indicate that a person is a carrier
- indicate a need for further testing
- Negative: This indicates a person has no changes in the gene, chromosome, or proteins of interest. However, it does not entirely rule out the possibility of developing the condition, as other factors may play a role. Depending on why it is done, results can:
- mean a person is unaffected by a genetic disorder
- indicate a person is not a carrier
- indicate a person does not have an increased risk for a particular condition
- Inconclusive: This means the test did not provide a clear answer. A doctor may recommend further testing or monitoring.
Genetic counseling can help individuals understand what the results mean.
Genetic counselors often specialize in specific areas, such as prenatal, pediatric, or cancer counseling. They may also work in other fields such as cardiovascular health or psychiatry.
Coping with results
Accepting genetic test results can be challenging. Support systems, such as counseling, are essential to help process the information.
Positive results lead to making hard decisions about preventive measures, while negative results may provide relief but could also lead to continued uncertainty.
What can genetic testing detect?
Genetic testing can detect inherited genetic disorders, predispositions to certain diseases, carrier status for specific conditions, and how individuals may respond to certain medications.
Does insurance cover genetic testing?
Many insurance plans cover genetic testing, especially when it may be medically necessary. However, coverage can vary, and it is important to verify this with the insurance provider before proceeding with the test.
What are the three types of genetic testing?
The three main types of genetic testing include:
- cytogenetic, which involves examining whole chromosomes
- biochemical, which involves measuring protein produced by genes
- molecular, which involves looking for small DNA mutations
How much does it cost to do a genetic test?
The cost of genetic testing can range from a few hundred to several thousand dollars, depending on the type and complexity of the test. Insurance coverage varies, so it is essential to check with an insurance provider.
Genetic testing can identify genetic mutations or variants associated with various diseases and conditions. Several types of genetic tests exist, each serving different purposes, such as diagnosing genetic disorders, guiding treatment, or assessing disease risk.
Preparing for genetic testing involves consultation, collecting a sample, and understanding the implications of the results. Genetic counseling can help individuals navigate the outcomes, whether the results are positive, negative, or inconclusive.
Genetic testing can aid in making informed decisions about health and treatment.