Over the past few years, DTC (direct-to-consumer) clinical genetic testing kits have been flying off the shelves as people jump for a chance to learn about their ancestry or determine whether they’re at risk for a genetic condition. The popular personal genomics and DTC testing kit manufacturer 23andMe alone boasts more than 10 million customers, according to the company’s website.
But with the popularity of these tests come many questions. Namely: what’s the difference between clinical genetic testing and DTC genome testing kits like 23andMe?
Here’s what you need to know.
How DNA Testing Works
A person’s DNA is much like code written for computers to perform various tasks it helps instruct many things, from creating the building blocks of the body itself, to influencing how the body performs its many functions. For example, DNA directs how amino acids come together into proteins, and how those proteins create cells. Cells form tissue, and tissue forms organs.
DNA is passed down by your parents, which is why children often share many of the same physical traits as their parents and parents’ biological relatives.
DNA testing examines a person’s “genetic fingerprint” (i.e., their DNA code) to help them trace their lineage back several generations or to help detect genetic markers of various diseases.
DTC Kits are Limited and May Require Further Testing
To test DNA, customers perform a mouth swab, or spit into a tube, and send the kit back to the company for analysis. DTC kits usually serve one of three purposes. First, customers can learn more about where in the world their ancestors come from, or to identify other (sometimes unexpected) relatives who have also taken the same DTC test. Second, customers can obtain “recreational genetics” results, such as prediction of eye color or earwax type. For these two purposes, many DTC kits work well. On the other hand, what someone can or can’t learn from a health-related DTC kit is more complicated.
DTC kits such as those of 23andMe can serve as a preliminary screen for a limited number of causes of genetic disease. The health testing through DTC kits at companies such as 23andMe solely tests for a minority of genetic causes of a minority of genetic diseases. For example, if you’re concerned about a genetic risk of pancreatic cancer, you may only learn about a few of the many possible genetic causes. A negative test doesn’t mean you’re in the clear. Don’t forget that these tests must also be confirmed using a clinical genetic test with a healthcare professional before they can be trusted for medical decision-making.
While DTC kits may be useful in detecting genetic markers , they’re still difficult to interpret without the assistance of a genetic counselor or other medical professional, and additional testing..
Clinical Genetic Testing is Specific to the Patient and of Higher Quality
Unlike DTC kits, clinical genetic testing is administered by a healthcare professional.Typically the clinician will collect DNA from a sample of saliva or blood. Samples are sent to labs where the material is studied for harmful changes in DNA.
Clinical genetic testing is specific to the medical and family history of the patient, and thus is typically comprehensive of the possible genetic causes of disease. Such testing rarely needs to be repeated for the purposes of quality. When testing takes place within the healthcare system, the results are explained and used in a way that is specific and relevant to the patient’s needs and concerns.
Clinicians often use clinical genetic tests such as what’s offered by Ariel to help in the diagnosis of a disease or to better understand the root cause of a person’s existing condition. Having this information allows clinicians to develop more personalized care plans and waste less time testing treatments that may or may not effectively treat a patient’s symptoms.
The better doctors understand the origins of genetic diseases, the better they can predict which prevention strategies or treatments will work best, as well as a disease’s trajectory. It can also lead to earlier diagnosis and help patients with hard-to-treat diseases like pancreatitis, for which even limited DTC testing is not yet available.
While 23andMe and other DTC tests can provide consumers with valuable information about their family history and health, they should never be used as a substitute for clinical genetic testing. By seeking genetic tests through a genetic counselor or other healthcare professional, patients have a better chance of receiving the best personalized care available.