- Genetic testing is an important health-care tool that can tell people a lot about their bodies.
- These tests analyze a sample of a person's DNA and look for specific changes associated with different conditions.
- Often, test results can help doctors diagnose and predict a person's risk for developing a disease.
- Other DNA tests can tell people about whether they're predisposed to certain traits.
- INSIDER spoke with Dr. William G. Feero, M.D., Ph.D., an associate professor of Community and Family Medicine at the Geisel School of Medicine at Dartmouth, to get a better understanding of how different genetic DNA tests work, and what they can teach people about their health.
- Visit INSIDER's homepage for more stories.
Top editors give you the stories you want — delivered right to your inbox each weekday.
Thanks for signing up!
Access your favorite topics in a personalized feed while you're on the go.
Getting a DNA test can give you a window into your health.
Today, there are numerous genetic tests available to people at the clinical and consumer level. In general, they involve a mouth swab, hair sample, or a blood test to allow doctors, scientists, and individuals to look closely at a person's DNA for variations (mutations) that are linked to particular traits or conditions.
But it's important to note that clinical and consumer tests are not created equal. In fact, many home DNA tests aren't regulated to the degree that medical DNA tests are.
INSIDER spoke with Dr. William G. Feero, MD, PhD, associate professor of Community and Family Medicine at the Geisel School of Medicine at Dartmouth, to learn how medical DNA tests work and the different ways they can be useful for understanding our health. Regardless of your motivations for seeking DNA testing, you should always consult a physician about interpreting your results.
Diagnostic tests can confirm whether you have a hereditary disease like Huntington's disease, sickle cell anemia, Marfan syndrome, and cystic fibrosis
Most of the time, doctors use genetic testing as a tool to help confirm a genetic disease diagnosis in patients who are experiencing specific symptoms, said Feero.
During a medical DNA test, a licensed practitioner such as a nurse or doctor collects a small sample of hair, skin, saliva, or blood from a patient. Pregnant people may also give a sample of amniotic fluid (aka the liquid around an unborn child.)
According to the National Institutes of Health, genetic tests (at the clinical level) can be used to identify 2,000 hereditary diseases and conditions. Some examples of common hereditary diseases that these tests might find include cystic fibrosis, familial hyperlipidemia, and muscular dystrophy.
"Diagnostic genetic tests look for specific changes in the DNA, in specific genes that are relatively well-proven to cause those genes not to work properly, and for the person to develop disease," Feero said. "They are highly reliable and very accurate."
One of the benefits of these types of genetic tests is that they allow doctors to detect hereditary diseases at every stage of life. In some cases, if doctors are able to identify the disease before symptoms progress to a severe level, they can help patients plan for managing the condition.
This is especially useful for conditions like familial hyperlipidemia, which can result in premature heart attacks and stroke. Catching these types of diseases during their early stages (as in, before a first heart attack) means a patient will possibly have more options for treating the disease.
This type of testing is usually only done in a health-care setting.
Presymptomatic genetic tests may tell you whether you're going to eventually develop a (hereditary) disease you don't actually have yet
When a healthy person with no symptoms has a documented family history of a disease, such as diabetes, genetic tests can analyze specific markers in their genes that are related to that disease, said Feero.Doctors may then use this information to predict whether that person is at risk of developing the condition.
"One clear cut example is Huntington's disease. It is a single-gene disorder that causes dementia, and it usually starts when someone is in their 50s or 60s," he told INSIDER. "If you have the mutation associated with that disease, you are 100% going to get it. (In the case of Huntington's disease, that mutation is an expansion of the region of DNA in a particular gene.)"
But when it comes to diseases that involve multiple mutations, occurring in one or a few genes, determining a person's risk is a little more complex, said Feero. Some conditions aren't just caused by changes in a single gene, but rather, a whole range of changes across, potentially, multiple genes. Feero said genetic testing can be useful by allowing doctors to analyze the different types of gene changes. This can give them an idea of whether someone will get a disease, how bad it will be, and perhaps insights on potential treatments.
A carrier test can tell you if your DNA contains a mutation for a genetic disorder that might affect your unborn child
Sometimes people who are totally healthy can have mutations in their DNA that are associated with different genetic disorders, explained Feero. This is called being a carrier, and it basically means their DNA inherited a single copy of the gene mutation for that hereditary condition or disease. Generally, the condition doesn't actually affect that person or their health, because their DNA still has an additional copy of that same gene that doesn't have the mutation.
For example, if you're a carrier for a disease mutation linked to cystic fibrosis, it doesn't mean you have cystic fibrosis. But there's a 50% chance that you will pass along a copy of that same mutation to your future children, and cause them to also be a carrier for that condition. However, when two future parents turn out to be carriers for the same genetic disorder, their child may develop the disease, explained Feero.
He told INSIDER, "If a woman is a carrier of a mutation for cystic fibrosis, and her partner is also a carrier of a mutation in one of his cystic fibrosis genes, their baby has a one in four chance of inheriting two bad copies of those genes. [As a result,] there's an increased chance that baby will be born with cystic fibrosis."
Expanded carrier status screening is a type of genetic DNA test that can estimate reproductive risks in healthy individuals, said Feero.
He told INSIDER, "Expanded carrier status screening can be useful if you are a woman who is contemplating pregnancy, and you want to know what genetic changes you might have in your DNA that could predict risk for multiple relatively rare, serious diseases in your newborn. For example, [certain] changes in your DNA might be associated with cystic fibrosis or Tay-Sachs risk for the baby."
Today, many fertility clinics and other health-care facilities offer tests that can tell you if you are a carrier for different genetic disorders. There are also several direct-to-consumer DNA tests that provide these types of results, too.
According to the National Human Genome Research Institute, hereditary conditions that might be detected in a carrier test include Huntington's disease, sickle cell anemia, spinal muscular atrophy, polycystic kidney disease, Tay-Sachs disease, and Down syndrome.
Knowing this information allows parents to make well-informed choices about family planning.
A predictive genetic test may give you an idea of your risk for developing some hereditary cancers, but they aren't 100% certain
According to the National Cancer Institute, some genetic tests can provide people with information about whether they inherited mutations associated with several types of hereditary cancer. This includes certain types of breast cancer, colon cancer, melanoma, and sarcoma. One well-known cancer-related mutation that a DNA might check for is the BRCA 1/BRCA 2 gene mutation.
"If you have one of those classic BRCA genes mutations, your risk of developing breast cancer is very high," said Feero.
For some people, receiving genetic test results that come back positive for a mutation like this can be life-changing. Feero noted this can make that person eligible for additional tests like ovarian cancer and breast cancer screenings, starting at an early age. It may also influence them to talk with their family members about potentially getting tested for mutation as well.
And depending on the other risk factors a person has (like their weight, diet, and other health conditions), it may lead them to take further action to help prevent the disease before it begins. In this case, if someone has the BRCA 1 or BRCA 2 gene mutation, along with other risk factors, they may decide to get a mastectomy (breast removal) to minimize their chances of cancer occurring.
However, it's important to remember that not all cancers are caused by hereditary mutations. In fact, many of the mutations that cause cancers are sporadic, which means they happen randomly and unexpectedly due to environmental factors. This means a genetic test can't always say for certain whether someone will get cancer, said Feero.
Conversely, if someone does have the BRCA 1 or BRCA 2 gene mutation, it doesn't mean they're 100% guaranteed to get breast cancer, either (though their risk is MUCH higher than the general population).
Still, if you have a family history of cancer and you're concerned about your risk, you should talk with your doctor about this type of testing.
Depending on the type of DNA test you get, you may also be able to learn about whether you have some increased risk for developing conditions that are caused by multiple factors, like diabetes
Using genetics to predict whether someone will develop a disease is a very complex process. Tests that are done in a clinical setting like a doctor's office may look for different things than a DNA test you can buy at home. A direct-to-consumer test usually involves a swab that is then mailed into a lab.
"Direct-to-consumer DNA tests use what is called SNP-based [pronounced 'snip'], or single-based nucleotide polymorphism testing. They look for changes in DNA that are associated potentially with mutations that actually cause disease, that often aren't the mutations themselves," Feero told INSIDER.
Most of the time, these tests can tell you if your DNA shows variations that make you predisposed to developing a disease or condition. But this type of result is a lot different than saying you're definitely going to get a disease.
This is especially the case when it comes to diseases where your genes and lifestyle choices play a role in whether you get it. Results from a SNP test are just one piece of the puzzle, while other factors like your diet, fitness level, blood pressure, and environment also contribute to whether you'll get that disease.
Currently, the FDA says that some DNA tests are approved to share information regarding a person's genetic health risk for developing 10 medical conditions, including Parkinson's disease, celiac disease, Late-onset Alzheimer's (a progressive brain disorder that affects memory), along with several blood-clotting and tissue disorders.
Still, Feero noted much the mainstream medical community remains uncertain about how accurate and useful these polygenic risk scores are in predicting whether someone will get a disease.
"These risk scores for conditions like type 2 diabetes are really probabilistic," said Feero. "They predict some increased risk, but are definitely not deterministic, which means they don't tell you for certain that you will develop type 2 diabetes. Often the increased risk predicted only accounts for a small amount of the total risk a person has for developing a disease."
He added that it's important to consider these genetic risk scores only account for one portion of your risk.
"People should be careful about evaluating their reasons for seeking DNA testing," said Feero. "They should try to understand from a knowledgeable healthcare provider what the test can and can't tell them about the particular health conditions they may be interested in testing for."
Some home DNA tests may be capable of telling you whether you're likely to have certain traits like lactose intolerance or a higher body weight
Many consumer DNA tests now provide people with information that isn't related to whether or not they have a serious genetic disorder.
SNP testing can detect variations in a person's genome that are associated with different traits that aren't necessarily diseases as well as medical conditions, said Feero. As is the case for diseases in which multiple genetic variants play a role, the associations for traits are made based on research that has linked genetic variations in certain populations to these traits. By comparing your DNA to the DNA of others with these traits, these tests can infer traits you might have.
For example, some test results might tell a person if they're predisposed to lactose intolerance or moving around when they sleep.
It's important to note these trait tests, as well as SNP-based tests for disease risk, do have limitations
Feero pointed out that one issue with these consumer tests is that they only test for a limited number of relatively common genetic variants. This can be problematic if you're someone from an underrepresented population because your results might not be as accurate as those for someone from a population group that has been extensively studied for associations between variants and traits and diseases.
And even if you are from a population that has been well studied and is highly represented in available research databases, it's important to remember these SNP-based test results are not considered a medical diagnosis.
But that doesn't mean they can't be beneficial to you. Learning that you may be predisposed to a certain trait might influence you to make positive lifestyle changes that can improve your health overall. For instance, if you learn that you're more likely to have a higher weight than the average person, you might feel inspired to work out more often at the gym or start a new fitness plan. In addition, some results may encourage you to have important conversations with your doctor about your diet or fitness plan.
But as far validity goes, perhaps it's best to take these types of results with a grain of salt.
What can a DNA test tell me about my health? ›
A DNA test (genetic testing) is a medical test that can identify mutations in your genes, chromosomes or proteins. These mutations can indicate if you have or don't have a genetic condition. DNA tests can also identify your risk for developing a certain condition or passing on a genetic disorder.What are the top 4 things you would test using DNA testing? ›
- Forensic. Of course, forensics is still a primary reason for having DNA tested. ...
- Immigration. Immigration is a hot button issue in America. ...
- Infidelity. Everybody worries about the loyalty of their significant other. ...
- Paternity. ...
Most DNA tests provide basic information about your DNA, ancestry, and genetic health risks. However, services like 23andMe and Ancestry may be more well-suited for people who want to learn more about their ancestry and living relatives, while Invitae is best for learning more about health risks.Can a DNA test really tell you what you should and should not be eating? ›
The data from genetic nutrition tests aren't good enough to give individual diet advice. “In reality, there is no evidence that you can use genes to identify which foods you should and shouldn't eat, with very few exceptions," Tim says.Can DNA detect diseases? ›
Genetic testing can reveal changes (mutations) in your genes that may cause illness or disease. Although genetic testing can provide important information for diagnosing, treating and preventing illness, there are limitations.What are 4 things that DNA determines in your body? ›
DNA contains all the information needed to build your body. Did you know that your DNA determines things such as your eye color, hair color, height, and even the size of your nose? The DNA in your cells is responsible for these physical attribute as well as many others that you will soon see.What are 3 ways DNA testing might be used for? ›
DNA testing is a method that takes samples of a person's DNA, which could be their hair, fingernail, skin, or blood, to analyze the structure of that person's genome. DNA testing can help establish parentage (or lack thereof), ancestral history, and even help police investigate a crime scene.What diseases can genetic testing find? ›
- cystic fibrosis.
- Tay-Sachs disease.
- sickle cell disease.
- Down syndrome.
- spina bifida.
- Turner syndrome.
- von Willebrand Disease.
DNA test can provide a lot of information about your health and body, including preventing predisposed illnesses. The reports of your DNA test can help your doctor to plan your health checkups, and guide you about the lifestyle changes you need to make.Are health DNA tests worth it? ›
The obvious benefit of genetic testing is the chance to better understand your risk for a certain disease, such as cancer. Testing is not perfect, but it can often help you make decisions about your health.
Can DNA tell allergies? ›
A commercially-available DNA test won't tell you for certain whether you currently have a specific allergy or intolerance. For example, genetics only account for up to 6% of the risk for a peanut allergy—other environmental factors also play a critical role.What can DNA not tell you? ›
DNA can help us understand how our bodies work and tell us more about who we are, but it can't solve every mystery about our health. Most importantly, remember that no DNA test can tell you how to feel or what your future might hold. These things are as individual and unique to each of us as our fingerprints.Can DNA test help with weight loss? ›
DNA testing cannot help you lose weight in its own right, but it can help you and your dietitian put together a diet and exercise plan that is in line with your genetics. Scientists have recently compared the effectiveness of weight loss groups with and without the use of DNA testing.What are the 10 common genetic disorders? ›
What are common genetic disorders?
- Down syndrome (Trisomy 21).
- FragileX syndrome.
- Klinefelter syndrome.
- Triple-X syndrome.
- Turner syndrome.
- Trisomy 18.
- Trisomy 13.
|Autosomal dominant||Huntington disease, Marfan syndrome|
|Autosomal recessive||cystic fibrosis, sickle cell disease|
|X-linked dominant||fragile X syndrome|
|X-linked recessive||hemophilia, Fabry disease|
What are the signs of good genes? Good gene indicators are hypothesized to include masculinity, physical attractiveness, muscularity, symmetry, intelligence, and “confrontativeness” (Gangestad, Garver-Apgar, and Simpson, 2007).What are 3 types of genetic tests? ›
- Molecular tests look for changes in one or more genes. ...
- Chromosomal tests analyze whole chromosomes or long lengths of DNA to identify large-scale changes. ...
- Gene expression tests look at which genes are turned on or off (expressed) in different types of cells.
Law enforcement has solved countless cold cases as well as current cases based on DNA evidence. The problem arises from the fact that, like almost everything, DNA testing is not 100% reliable. A miscarriage of justice can result when someone gets wrongfully convicted based on incorrect DNA results or interpretations.What do daughters inherit from their mothers? ›
The mitochondrial genes always pass from the mother to the child. Fathers get their mitochondrial genes from their mothers, and do not pass them to their children.What does A child inherit from their father? ›
We inherit a set of 23 chromosomes from our mothers and another set of 23 from our fathers. One of those pairs are the chromosomes that determine the biological sex of a child – girls have an XX pair and boys have an XY pair, with very rare exceptions in certain disorders.
What facial features are inherited from father? ›
As well as the tip of your nose (which is 66% likely to be passed down from a parent), the other most-inherited features were your philtrum (the area directly beneath your nose), your cheekbones, the inner corners of your eyes, and the areas both above and below your lips.What are the 5 uses of a DNA profile? ›
DNA profiling is a forensic technique in criminal investigations, comparing criminal suspects' profiles to DNA evidence so as to assess the likelihood of their involvement in the crime. It is also used in paternity testing, to establish immigration eligibility, and in genealogical and medical research.Do twins have the same DNA? ›
Identical twins share the same genomes and are always of the same sex. In contrast, fraternal (dizygotic) twins result from the fertilization of two separate eggs with two different sperm during the same pregnancy. They share half of their genomes, just like any other siblings.How often is DNA evidence wrong? ›
Studies have shown that DNA evidence is 99% accurate, making it one of the most foolproof pieces of evidence you can possibly use in court. Like fingerprints, no two people have the same DNA. If a mistake occurs, it's typically because of human error.What are the 2 most common samples used for DNA testing? ›
The most common reference samples collected from known individuals are blood, oral/buccal swabs, and/or plucked hairs (e.g., head, pubic).Why should I do a DNA test? ›
Direct-to-consumer genetic testing promotes awareness of genetic diseases. It provides personalized information about your health, disease risk, and other traits. It may help you be more proactive about your health. It does not require approval from a healthcare provider or health insurance company.How does DNA identify a person? ›
Each person's nuclear DNA is unique—except for identical twins, who have the same DNA. When a sufficient nuclear DNA profile from the victim's remains matches the nuclear DNA profile from a sample known to have come from the victim, we can be very sure of the identity of the victim.What genes are inherited from father only? ›
What genes are only inherited from father? Sons can only inherit a Y chromosome from dad, which means all traits that are only found on the Y chromosome come from dad, not mom. Background: All men inherit a Y chromosome from their father, and all fathers pass down a Y chromosome to their sons.What cancers can be detected through genetic testing? ›
- Breast cancer.
- Ovarian cancer.
- Colon cancer.
- Thyroid cancer.
- Prostate cancer.
- Pancreatic cancer.
Thanks to the sequencing of all genes using next generation sequencing (NGS) techniques, we can determine the presence of variants associated with autoimmune diseases.
How reliable is genetic testing in predicting diseases? ›
Genetic testing can provide only limited information about an inherited condition. The test often can't determine if a person will show symptoms of a disorder, how severe the symptoms will be, or whether the disorder will progress over time.Are allergies inherited from mother or father? ›
Summary: New research found that, compared with a father's traits related to allergies and asthma, a mother's traits create a higher risk that a child will develop these same traits in early childhood.What does genetic testing look for? ›
Genetic testing looks for changes, sometimes called mutations or variants, in your DNA. Genetic testing is useful in many areas of medicine and can change the medical care you or your family member receives.Do you inherit your parents allergies? ›
The tendency to develop allergies is often hereditary, which means it can be passed down through genes from parents to their kids. But just because a parent has allergies doesn't mean that their kids definitely will get them.Can siblings have different DNA? ›
Because of recombination, siblings only share about 50 percent of the same DNA, on average, Dennis says. So while biological siblings have the same family tree, their genetic code might be different in at least one of the areas looked at in a given test. That's true even for fraternal twins.What information does your DNA hold? ›
DNA contains the instructions needed for an organism to develop, survive and reproduce. To carry out these functions, DNA sequences must be converted into messages that can be used to produce proteins, which are the complex molecules that do most of the work in our bodies.Can DNA show what you look like? ›
Scientists can now, with some certainty, use a strand of DNA to identify an individual's likely hair and eye color, as well as skin pigmentation and ancestry.Which DNA test is best for health? ›
Most DNA tests provide basic information about your DNA, ancestry, and genetic health risks. However, services like 23andMe and Ancestry may be more well-suited for people who want to learn more about their ancestry and living relatives, while Invitae is best for learning more about health risks.Does obesity affect DNA? ›
It indicates that obesity can impact genome stability. Oxidative stress and inflammation, commonly occurring in obesity, can induce DNA damage and inhibit DNA repair mechanisms. Accumulation of DNA damage can lead to an enhanced mutation rate and can alter gene expression resulting in disturbances in cell metabolism.Should you eat before a DNA test? ›
Do not eat, drink, smoke, chew gum, brush your teeth, or use mouthwash for at least 30 minutes prior to providing your sample. Collect the recommended volume of saliva. The recommended volume of saliva to provide is about 2 mL, or about ½ teaspoon. Your saliva sample should be just above the fill line.
How accurate are DNA health reports? ›
Each variant in our Genetic Health Risk and Carrier Status Reports demonstrated >99% accuracy, and each variant also showed >99% reproducibility when tested under different laboratory conditions.Does Ancestrydna show health issues? ›
Currently, these tests include certain cancer risks, such as hereditary breast and ovarian cancer syndrome and Lynch syndrome; carrier status for cystic fibrosis, sickle cell anemia, and Tay-Sachs disease; and heart and blood health conditions cardiomyopathy, familial hypercholesterolemia, hereditary hemochromatosis, ...What are the disadvantages of DNA testing? ›
- Testing may increase your stress and anxiety.
- Results in some cases may return inconclusive or uncertain.
- Negative impact on family and personal relationships.
- You might not be eligible if you do not fit certain criteria required for testing.
Genetic testing is useful in many areas of medicine and can change the medical care you or your family member receives. For example, genetic testing can provide a diagnosis for a genetic condition such as Fragile X or information about your risk to develop cancer. There are many different kinds of genetic tests.What can fail a DNA test? ›
Common reasons a sample may fail
This can happen if the cap is installed incorrectly or not screwed on tightly enough. The blue stabilizing solution did not mix well enough with the saliva sample. Contamination (something other than human saliva and stabilizing liquid in the collection tube), including: bacteria.
Arguments against genetic screening
Some feel that genetic screening would lead to discrimination of those individuals, which possess "inferior" genes. Second, people fear that genetic screening will lead to reproductive decisions being based on the genetics of their child.
A DNA paternity test is nearly 100% accurate at determining whether a man is another person's biological father. DNA tests can use cheek swabs or blood tests. You must have the test done in a medical setting if you need results for legal reasons.What health traits are on Ancestry? ›
AncestryDNA currently offers 40 traits: alcohol flush, asparagus metabolite detection, beta-carotene, birth weight, bitter sensitivity, caffeine consumption, cilantro aversion, cleft chin, earlobe type, earwax type, endurance fitness, eye color, facial hair thickness, finger length, freckles, hair color, hair strand ...Does AncestryDNA test for Alzheimer's? ›
While a direct-to-consumer genetic test can estimate your risk, it cannot tell you for certain whether you will or will not develop Alzheimer disease. Variations in multiple genes, together with lifestyle factors such as diet and exercise, all play a role in determining a person's risk.What can 23andMe tell you? ›
23andMe® brings the world of genetics to you. 23andMe analyzes variations at specific positions in your genome. These variations, called SNPs (Single Nucleotide Polymorphisms), have the potential to tell you about your traits—such as eye or hair color—and certain health conditions.