Genetic testing is a type of medical test that identifies changes in a person's genes, chromosomes, or proteins. By examining an individual's DNA, these tests can confirm or rule out a suspected genetic condition, or help determine a person's risk of developing or passing on a genetic disorder.

How genetic testing works

Genetic testing can be performed using a small sample of bodily fluid or tissue, such as blood, saliva, or cells from the inside of the cheek. The sample is sent to a laboratory, where technicians look for specific changes, such as:

* Gene variations: Analyzing specific DNA sequences to find variants or mutations linked to a genetic disorder.
* Chromosomal abnormalities: Examining entire chromosomes or long segments of DNA to find large-scale changes, like a missing or extra chromosome.
* Protein or enzyme levels: Measuring the amount or activity of certain proteins, as abnormalities can indicate DNA changes causing a genetic disorder.

Types of genetic testing

There are several types of genetic tests, each used for a different purpose:
Diagnostic testing: Confirms or rules out a specific genetic condition in a person who is already showing symptoms.
Predictive and presymptomatic testing: Detects gene mutations that increase a person's risk of developing a genetic disorder later in life, such as certain cancers. This is often recommended for individuals with a family history of a specific condition.
Carrier testing: Determines if a person carries a gene for a recessive disorder, such as cystic fibrosis. This is typically done before or during pregnancy to assess the risk of passing the condition to a child.
Prenatal testing: Detects genetic abnormalities in a fetus during pregnancy using a sample of the mother's blood or other procedures like amniocentesis.
Newborn screening: The most widespread type of genetic testing, it identifies genetic or metabolic disorders in newborns so that treatment can begin immediately.
Pharmacogenomic testing: Determines how an individual's genetic makeup affects their response to specific medications, which helps doctors choose the safest and most effective drug treatments.

Benefits and limitations

Genetic testing offers important benefits, but it also has limitations and potential risks.
Benefits:
Informed decisions: The results can help individuals and their families make informed decisions about their healthcare and family planning.
Earlier treatment: For some conditions, early diagnosis can lead to prompt treatment, improving a person's health outcomes.
Personalized medicine: For certain cancers, genetic testing on tumor cells can help determine the most effective, personalized treatment plan.

Limitations and risks:

Uncertain results: Some tests may yield an uncertain result (a variant of uncertain significance, or VUS), where it is not yet clear if the genetic change is benign or disease-causing.
Risk of discrimination: Concerns about genetic discrimination by insurance companies or employers led to the passage of laws, such as the Genetic Information Nondiscrimination Act (GINA) in the U.S., but protections may vary.
Emotional impact: A positive test result can cause anxiety, guilt, or depression, which is why genetic counseling is a crucial part of the testing process.
Accuracy limitations: Genetic tests do not always have 100% accuracy and may not be able to predict the exact symptoms, severity, or progression of a disorder.