Tests that are marketed directly to consumers without the involvement of a health care provider are called direct-to-consumer tests (also referred to as DTC). These tests generally request the consumer collect a specimen, such as saliva or urine, and send it to the company for testing and analysis.

Direct-to-consumer testing is expanding the number of people who are able to get genetic testing of their DNA (or genome). Your genome is made up of thousands of genes that carry the hereditary information about your traits, such as eye color or height. This information is based on the arrangement of distinct molecules (also known as "bases") that make up genes. Some of these arrangements, or variants, can be used to diagnose a rare disease, provide information about a person's risk of developing disease, or other types of information. Some variants have clinical significance and may give consumers insight into monitoring their own health, or about potential disease or conditions.

Not all direct-to-consumer tests are genetic tests, though the majority on the market today are. Some measure other things, such as levels of proteins in your body, levels of toxins in urine, or levels and types of bacterial flora (referred to as a "microbiome").

Direct-to-consumer tests have varying levels of evidence that support their claims. Some direct-to-consumer tests have a lot of scientific and clinical data to support the information they are providing, while other tests do not have as much supporting data. There can also be disagreements in the clinical community about the role that different genetic variants have in contributing to disease, and new information is being learned every day. There are tens of thousands of variants and varying information available to determine whether those variants are relevant to whether a person may get a disease or condition. Not all variants that contribute to a person's risk of getting a disease or condition may be known, so it is important that consumers understand that a negative result means they still may be at risk for a particular disease or condition.

Not all direct-to-consumer genetic test companies test for the same set of variants, and therefore may provide different results for the same disease or condition. Therefore, consumers must use their judgment when ordering and interpreting their results from these tests. Consumers should consider discussing their results with a genetic counselor or a qualified health care provider to better understand the clinical relevance of the result to their own health.

Did you know that anyone can buy a test that will read specific places in their DNA and provide them with information about their genome? Advances in genomics since the Human Genome Project have led to an explosion in at-home, or "direct to consumer" genomic testing. You can even seek genomic information without involving a healthcare provider in ordering the test or delivering the results. What are the pros and cons?

There are now numerous companies offering you a service to learn more about yourself or your family through DNA testing - maybe you've seen ads on TV or heard them on the radio. The global "direct-to-consumer" (or DTC) genomic testing market was valued at $117 million in 2017, suggesting millions of people are purchasing these tests. In contrast to clinical genomic testing, such as for cancer and prenatal screening in which a healthcare provider orders the tests and provides the results, DTC genomic tests can be purchased online or even at your local pharmacy.

Learn from DTC Genomic Testing

One popular application of such DTC genomic testing is for revealing family ancestry or genealogy. For example, the company Ancestry.com started as a place to search historical and family records to gain genealogical clues, and has now expanded to offer genomic tests for people who seek information about their genomic ancestry. As of February 2018, more than seven million customers had purchased the test from this company alone. Popular TV shows, such as "Who Do You Think You Are?", have featured their test and information.

Another prominent company, 23andMe, was established in 2006 with the goal of offering genomic testing directly to people interested in getting DNA-based health, traits, and ancestry information. Some of the information reported back to customers are surprising factoids, such as whether you have dry or wet earwax due to genomic variants or if you are likely to prefer salty/savory snacks compared to sweets. They also offer their customers the opportunity to provide their genomic information to large research studies [see Social Context], such as recruiting 25,000 people for a study on the genomics of schizophrenia and bipolar disorder. These research studies can provide another avenue to advance genomic science and improve human health on a rapid basis.

Risks and Limitations

In the last few years, there have been a number of stories involving people who found new family members or famous relativesthrough DTC genomic testing. Some people have found out that family members who they previously thought were genetic relatives were actually not biologically related to them, or even that their own identity is not what they thought. It's best to ask yourself several questions before taking any DTC genomic test: Is the company reputable? Is the science behind the test solid and independently validated? Has the specific test you are interested in been approved by the U.S. Food and Drug Administration (FDA) if it is about your health? How will you handle the information from the test? Will you want to speak to a genetic counselor or a healthcare provider about the test results?

Let's take one example. Some DTC genomic testing companies claim to provide information about a child's ability in certain sports. You want to find out if your daughter will be a sprinting champion. There is validated science behind the claim that certain variants in the gene ACTN3 control different types of muscle fibers (called "fast-twitch" or "slow-twitch"), and many successful sprinters have the "fast-twitch" genomic variants. But the prediction power stops there. ACTN3 variants are just one factor among many, many others - genomic, environmental, and social. So, even if your daughter does not have the "fast-twitch" genomic variant, that does not mean she cannot become an accomplished sprinter. Looking for genomic variants in children, such as the one for "fast-twitch" muscle fibers, also raises ethical questions. Since children may not be able to consent to such a test and/or they might be unable to fully understand what such testing might mean for them today or in their future, is it okay for parents to have their children tested? Might you treat your child differently based on the results?

Several professional organizations have published recommendations for DTC genomic testing, including the American Society of Human Genetics and the American College of Medical Genetics and Genomics. The National Institutes of Health offers an explanation of how genomic testing is regulated, which can help you investigate a specific test.

With direct-to-consumer genetic testing companies offering a variety of tests, it can be challenging to determine which tests will be most informative and helpful to you. When considering testing, think about what you hope to get out of the test. Some direct-to-consumer genetic tests are very specific (such as paternity tests), while other services provide a broad range of health, ancestry, and lifestyle information.

Major types of direct-to-consumer genetic tests include:

Disease risk and health

The results of these tests estimate your genetic risk of developing several common diseases that are caused by environmental factors and multiple variants in several genes. These common diseases include such as celiac disease, Parkinson's disease, and Alzheimer's disease. Some companies also include a person’s carrier status for less common conditions, including cystic fibrosis and sickle cell disease. A carrier is someone who has a gene variant in one copy of the gene that, when present in both copies of the gene, causes a genetic disorder. The tests may also look for certain genetic variations that could be related to other health-related traits, such as weight and metabolism (how a person’s body converts the nutrients from food into energy). These tests may also provide information about how a person may respond to certain drugs (pharmacogenomics). 

Ancestry or genealogy

The results of these tests provide clues about where a person's ancestors might have come from, their ethnicity, and genetic connections between families. For more information, see What is genetic ancestry testing?

Kinship

The results of these tests can indicate whether tested individuals are biologically related to one another. For example, kinship testing can establish whether one person is the biological father of another (paternity testing). 

Lifestyle

The results of these tests claim to provide information about lifestyle factors, such as nutrition, fitness, weight loss, skincare, sleep, and even your wine preferences, based on variations in your DNA. Many of the companies that offer this kind of testing also sell services, products, or programs that they customize on the basis of your test results.

Before choosing a direct-to-consumer genetic test, find out what kinds of health, ancestry, or other information will be reported to you. Most direct-to-consumer genetic tests do not sequence whole genes, but look at only a subset of variants within the genes associated with the conditions or traits they report on. For more comprehensive genetic testing, see a genetics professional. Think about whether there is any information you  would rather not know. In some cases, you can decline to find out specific information if you tell the company before it delivers your results. 

Direct-to-consumer genetic testing has both benefits and limitations, as they are somewhat different than those of genetic testing ordered by a healthcare provider.

Benefits

• 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.

• As results are provided directly to the individual, they are not in your insurance or medical record (unless you share results with your healthcare professional). 

• It is often less expensive than genetic testing obtained through a healthcare provider, which can make testing more accessible to people with no or limited health insurance.

• DNA sample collection is usually simple and noninvasive, and results are available quickly.

• Your anonymous data is added to a large database that can be used to further medical research. Depending on the company, the database may represent up to several million participants.

Risks and limitations

• Tests may not be available for the health conditions or traits that interest you.

• This type of testing cannot tell definitively whether you will or will not get a particular disease. Results often need to be confirmed with genetic tests administered by a healthcare professional.

• The tests look only at a subset of variants within genes, so disease-causing variants can be missed.

• Unexpected information that you receive about your health, family relationships, or ancestry may be stressful or upsetting.

• As testing is done outside of a healthcare clinic, individuals often are not provided with genetic counseling or thorough informed consent.

• People may make important decisions about disease treatment or prevention based on inaccurate, incomplete, or misunderstood information from their test results.

• There is currently little oversight or regulation of testing companies.

• Unproven or invalid tests can be misleading. There may not be enough scientific evidence to link a particular genetic variation with a given disease or trait.

• Genetic privacy may be compromised if testing companies use your genetic information in an unauthorized way or if your data is stolen.

• The results of genetic testing may impact your ability to obtain life, disability, or long-term care insurance.

Direct-to-consumer genetic testing provides only partial information about your health. Other genetic and environmental factors, lifestyle choices, and family medical history also affect the likelihood of developing many disorders. These factors would be discussed during a consultation with a doctor or genetic counselor, but in many cases they are not addressed when using at-home genetic tests.

Genetic ancestry testing, or genetic genealogy, is a way for people interested in family history (genealogy) to go beyond what they can learn from relatives or from historical documentation. Examination of DNA variations can provide clues about where a person's ancestors might have come from and about relationships between families. Certain patterns of genetic variation are often shared among people of particular backgrounds. The more closely related two individuals, families, or populations are, the more patterns of variation they typically share.

Three types of genetic ancestry testing are commonly used for genealogy:

Y chromosome testing

Variations in the Y chromosome can be used to explore ancestry in the direct male line. Only individuals with a Y chromosome (typically males) can have this type of testing done. However, people interested in this type of genetic testing sometimes recruit a relative to have the test done. Because the Y chromosome is passed on in the same pattern as are family names (surnames) in many cultures, Y chromosome testing is often used to investigate questions such as whether two families with the same surname are related.

Mitochondrial DNA testing

This type of testing identifies genetic variations in mitochondrial DNA. Although most DNA is packaged in chromosomes within the cell nucleus, cell structures called mitochondria also have a small amount of their own DNA (known as mitochondrial DNA). Both males and females have mitochondrial DNA so this type of testing can be used by either sex. Mitochondria DNA is passed on solely from egg cells so it provides information about the direct female ancestral line. Mitochondrial DNA testing can be useful for genealogy because it preserves information about female ancestors that may be lost from the historical record because of the way surnames are often passed down.

Single nucleotide polymorphism testing

These tests evaluate large numbers of individual variations (single nucleotide polymorphisms or SNPs) across a person’s entire genome. The results are compared to similar SNPs in a testing database to provide an estimate of a person's ethnic background. For example, the pattern of SNPs might indicate that a person's ancestry is approximately 50 percent African, 25 percent European, 20 percent Asian, and 5 percent unknown. (Sometimes, more regional specificity can be provided.) Genealogists use this type of test because Y chromosome and mitochondrial DNA test results, which represent only single ancestral lines, do not capture the overall ancestral background of an individual.

Genetic ancestry testing has a number of limitations. Test providers compare individuals' test results to different databases of SNPs, so ethnicity estimates may not be consistent from one provider to another. Additionally, these databases do not have equal coverage of SNPs for all ethnic populations; so results for minority populations may be nonspecific or inaccurate. Also, because most human populations have migrated many times throughout their history and mixed with nearby groups, ethnicity estimates based on genetic testing may differ from an individual's expectations. In ethnic groups with a smaller range of genetic variation due to the group's size and history, most members share many SNPs, and it may be difficult to distinguish people who have a relatively recent common ancestor, such as fourth cousins, from the group as a whole.

Genetic ancestry testing is offered by several companies and organizations. Most companies provide online forums and other services to allow people who have been tested to share and discuss their results with others, which may allow them to discover previously unknown relationships. On a larger scale, combined genetic ancestry test results from many people can be used by scientists to explore the history of populations as they arose, migrated, and mixed with other groups.

Genetic ancestry refers to information about the people that an individual is biologically descended from, including their genetic relationships. Genetic information can be combined with historical information to infer where an individual’s distant ancestors lived.

If you are interested in direct-to-consumer genetic testing, do some research into the companies that offer these services. Questions that can help you assess the quality and credibility of a testing company include:

• Does the company’s website appear professional? Do they have an app? Are both secure? Does the company provide adequate information about the services it offers, including sample reports, pricing, and methodology?

• Does the company have experienced genetics professionals, such as medical geneticists and genetic counselors, on its staff? Does the company offer consultation with a genetics professional if you have questions about your test results?

• Does the company explain which genetic variations it is testing for? Does it include the scientific evidence linking those variations with a particular disease or trait? Are the limitations of the test and the interpretation of results made clear?

• What kind of laboratory does the genetic testing, and is the laboratory inside or outside the United States? Is the laboratory certified or accredited? For example, does the laboratory meet U.S. federal regulatory standards called the Clinical Laboratory Improvement Amendments (CLIA)? Is the test approved by the U.S. Food and Drug Administration (FDA)?

• Does the company indicate how it will protect your privacy and keep your genetic data safe? Does that information include both current privacy practices and what may happen to your genetic data in the future?

• Does the company indicate who will have access to your data and how it may be shared? Does it share or sell their customers’ genetic data for research or other purposes? For some companies, much of their profit comes from selling large amounts of participant data for research and drug development, not from selling individual test kits.

Be sure to read and understand the “fine print” on the company’s website before purchasing a direct-to-consumer genetic test. This detailed information, which is often called the “terms of use” or “terms of service,” is a legally binding agreement between you and the company providing the testing. It spells out what is included and excluded in the service and details your rights and the company’s responsibilities. If you still have questions, contact the company to get more information before you make a decision about testing.

For most types of direct-to-consumer genetic testing, the process involves:

1. Purchasing a test

Test kits can be purchased online (and are shipped to your home) or at a store.  The price of some test kits includes the analysis and interpretation, while in other cases this information is purchased separately.

2. Collecting the sample

Collection of the DNA sample usually involves spitting saliva into a tube or swabbing the inside of your cheek and putting that swab into a tube. You then mail the sample as directed by the company. In some cases, you will need to visit a health clinic to have blood drawn.

3. Analyzing the sample

A laboratory will analyze the sample to look for particular genetic variations. The variations included in the test depend on the purpose of the test.

4. Receiving results

In most cases, you will be able to access your results on a secure website or app. (You will likely need to create an account on the testing company website to access results.) Other test companies share results in the mail or over the phone. The results usually include interpretation of what specific genetic variations may mean for your health or ancestry. At some companies, you can request additional explanation from a genetic counselor or other healthcare provider. This additional service may or may not involve an extra cost. Some testing companies may update your results over time based on new scientific information, such as a new genetic variant associated with a trait on their test.

The test kit will include step-by-step instructions, so be sure you understand them before you begin. If you have questions, contact the company before collecting your sample.

The price of direct-to-consumer genetic testing ranges from under a hundred dollars to thousands dollars. The cost depends on how many genetic variations are analyzed (and it will cost more if whole genome or whole exome sequencing is used), how extensive the interpretation of results is, and whether other products, programs, or services are included. Some companies charge separately for the sample collection kit and the analysis, while others offer the sample collection and analysis as part of a package. In some cases, consultation with a healthcare professional (such as a genetic counselor) is included in the cost of testing; in others, it can be added for an additional fee. Before you proceed with testing, make sure you know the total cost for all of the results, support, and other services you expect to receive.

Direct-to-consumer genetic tests, even tests that provide information about health and disease risk, are not covered by most health insurance plans. Because this testing is done without a referral from a healthcare provider and is not considered “diagnostic” (that is, it cannot be used to diagnose any disease or condition), health insurance companies generally will not pay for it. However, the tests may be eligible for reimbursement through flexible spending accounts (FSA) or health spending accounts (HSA) if the testing included health information. If you decide to share your results with your healthcare provider and he or she recommends additional testing or management, that follow-up care may be covered by insurance.

Direct-to-consumer genetic tests that are unrelated (or indirectly related) to health, such as ancestry testing and paternity testing, are typically not covered by FSAs, HSAs, or health insurance plans.

Direct-to-consumer genetic testing can provide interesting information about your health, traits, and ancestry. However, the results may not be clear-cut. Companies that provide these tests often tell their customers that the results are for information, education, and research purposes only—they are not meant to diagnose, prevent, or treat any disease or health condition. It is useful to keep this distinction in mind when interpreting your own test results.

Health and disease risk

The results of these genetic tests provide information about your chance of developing certain diseases (such as celiac disease or Parkinson's disease) and the likelihood that you have particular traits (such as dimples or lactose intolerance). These tests may also provide information about how a person may respond to certain drugs (pharmacogenomics). Test results are usually based on an analysis of one or more genetic variations that are known or suspected to be associated with the disease or trait. Direct-to-consumer genetic tests do not look at all genetic variants associated with diseases or traits.

The results of tests to predict disease risk do not provide a “yes or no” answer about whether a person will develop a given disease. Other factors, including genetic variations that were not tested, environmental factors, and lifestyle choices (such as diet and exercise) also contribute to disease risk in ways that may not be fully understood. Therefore, a result showing an increased risk does not mean you will definitely develop the disease, and a result showing a reduced risk does not mean you will never develop the disease.

Ancestry or genealogy

The results of these tests give clues about major geographic areas that are your family’s origins. These results are calculated on the basis of genetic variations that are more common in people from certain areas of the world than in others.

Sometimes the results of ancestry testing are unexpected or inconsistent with what a person understands about his or her family history. People who are closely related, such as siblings, may receive slightly different information about their ancestry because results are limited by the number and diversity of people who have submitted DNA samples to a given direct-to-consumer genetic testing company. It is important to be aware that receiving unexpected or ambiguous information about your background is a potential risk with this type of testing.

Kinship

The results of these tests give information about individuals who are likely related to you. (These individuals have also undergone testing, and the predictions are based on similarities among DNA sequences.) These tests can uncover previously unknown information about biological relationships among people (such as paternity). It is important to be aware that receiving unexpected or ambiguous information about your background or family is a potential risk with this type of testing.

Lifestyle

In most cases, direct-to-consumer lifestyle tests assess genetic variations related to very specific traits, such as how your body converts the nutrients from food into energy (metabolism), day/night (circadian) rhythm, or the senses of taste and smell. The company may recommend specific diet or fitness programs, dietary supplements, skincare products, or other products and services on the basis of your results. However, in most cases the link between a given genetic variation and a complex trait like weight, athletic performance, or sleep is indirect or unknown. Therefore, the results of these tests can be challenging to interpret, and it can be difficult to predict whether a recommended product or service will be helpful to you.

If you have questions about the meaning of your test results, professional support (such as guidance from a genetic counselor) may be available from the company that provided the test. You can also share questions about your results with your own healthcare provider. Talk to your doctor before making any major changes in managing your health, diet, or fitness after you receive results of a direct-to-consumer genetic test.

In addition to providing various reports and analyses based on your genetics, some direct-to-consumer genetic testing companies make your raw data available to download. The raw data are your genotype—the particular A’s, C’s, T’s, and G’s of your DNA—extracted from the sample you provided. These data are unique to you. Most companies caution that the raw data are only for research or education and are not suitable for medical purposes, such as diagnosing a disease.

It is challenging to interpret raw genotype data on your own. To help with this, several online “third-party interpretation” services offer analysis and interpretation of the raw data collected by another company. Third-party interpretation services can potentially use your genetic data to provide you with more information about your disease risk, traits, and ancestry. However, these services also have some risks and limitations:

• Relatively often, test results indicate an increased risk of disease when your risk is not actually higher than that of the general population. These errors can cause stress and anxiety.

• The results may include unexpected or upsetting information about your disease risk or family relationships without any context or guidance.

• The raw data, once you download it and send it by e-mail or store it on your computer, is no longer protected by the original service’s privacy measures.

• There is little regulation of third-party interpretation services.

As with any kind of genetic testing, it is important to assess the credibility of any company you are considering and find out how it protects your privacy before submitting your genetic information. Your healthcare provider can help you understand your results and determine whether any follow-up testing would be useful.

Carrier Screening Tests

These tests can be used to determine whether a healthy person carries a genetic variant that could be passed on to their potential future child(ren). These tests are for disorders where two copies of an abnormal gene variant must be present for the disease or condition to develop, meaning that each parent has one copy of the abnormal variant that could be passed on, giving the child a 25% chance of developing the disease or condition. These tests are intended to provide prospective parents information about whether they may be carriers for genetic diseases, are for use in adults of reproductive age, and produce results that should be used in combination with other available laboratory and clinical information.

Carrier screening tests are exempt from FDA premarket review, but they do need to follow specific requirements that are described in the regulation for this type of test.

Genetic Health Risk (GHR) Tests

GHR tests are intended to provide information on an individual's genetic risk for certain medical diseases or conditions. The information provided by these tests may help an individual make decisions about lifestyle choices and can inform discussions with a health care provider. The GHR tests are intended to provide genetic risk information to consumers, but these tests do not determine a person's overall risk of developing a disease or condition. In addition to the presence of certain genetic variants, there are many factors that contribute to the development of a health condition, including environmental, other genetic, and lifestyle factors.

Companies that offer DTC GHR tests are required to obtain FDA clearance prior to offering their first test. Companies may then offer most additional DTC GHR tests without FDA premarket review, provided they meet specific requirements that are described in the regulation for this type of test and are not for specific higher risk uses.

Pharmacogenetics Tests

Pharmacogenetics tests provide information regarding the role genetics may play in an individual's reaction to drugs. These tests inform consumers of genetic variants that may be related to how therapeutic drugs are metabolized in the body, or whether an individual is likely to respond to or have adverse reactions from certain therapeutic drugs.

Companies that offer DTC pharmacogenetic tests are required to come to FDA for premarket review and clearance. Currently the FDA has not authorized any DTC pharmacogenetic tests that predict whether an individual is likely to respond to or have adverse reactions from any specific therapeutic drug.

The FDA has issued a safety communication to alert the public of concerns regarding pharmacogenetic tests with unapproved claims to predict an individual's response to a specific therapeutic drug where these claims may not supported by clinical evidence.

Cancer Predisposition Tests

These tests provide information about an individual's risk of getting certain types of cancer. The information individuals obtain is intended to help them initiate a dialogue with their physician about whether they should be more closely followed for developing cancer or consider preventive treatment options intended to lower your chances of getting a cancer. An individual's physician will discuss with them their family history and other factors that may increase or decrease their risk.

These tests are considered moderate to high risk and are required to come to FDA for premarket review and clearance.

Low Risk General Wellness Tests

Some tests are offered for purposes the FDA considers general wellness, such as tests that predict athletic ability. The FDA generally does not review low risk general wellness products.

Ancestry Tests

Some tests are used to help individuals explore their genetic ancestry. The FDA does not review these types of tests.

While health-related reports resulting from direct-to-consumer tests are intended to empower consumers to take charge of their own health, and provide access to possibly important information, they do have some risks. Keep the following in mind when considering a direct-to-consumer test:

• Follow the directions provided with the test. If you do not follow the directions carefully there is a chance the test may not work correctly.
• Talk with your health care provider about which tests might provide useful information about your health. Make sure you understand the benefits as well as the limitations of any test before use. Labeling for FDA-reviewed tests describes the appropriate uses and limitations of the test.
• Do not make any dietary or health-related decisions without first discussing your test results with your health care provider. For genetic tests, you may also consider speaking with a genetic counselor, board-certified medical geneticist, or other equivalent health care provider.
• Understand that many factors can contribute to the development of a health condition, including environmental and lifestyle factors. Genetic risk is just one piece that may contribute to the development of a disease or condition.
• Some genetic health risk tests do not report all known genetic variants that might contribute to an increased risk of disease. Even if you receive a negative result for a genetic health risk test, you should continue with regular preventative care, such as annual checkups and screenings recommended by your health care provider. A positive result should also not be used to make decisions about treating a disease.
• A positive test could be stressful and upsetting, as you may learn information that suggests you might be at an increased risk for a disease or condition. Remember that a positive result from a test does not mean that you will develop that disease or condition.
• The Genetic Information Nondiscrimination Act (GINA) prevents health insurers from using your genetic information in coverage and rating determinations. GINA also prevents employers that have 15 or more employees from requesting or using your genetic information to make hiring, firing or promotion decisions. However, GINA does not cover certain other types of insurance. Receiving a genetic testing result may impact your purchase of life, disability, and long-term care insurance.
• Remember that direct-to-consumer tests are not a substitute for a traditional health care evaluation, including health screenings and visits to your health care provider.

Did you know that your genome helps uncover the history of your ancestors, both near and distant? Advances since the Human Genome Project allow us to compare genome sequences among humans, living and long-deceased, and to trace our collective ancestral history.

Where did different humans come from and how are we related? These are among the most common questions that humans ponder. The Human Genome Project produced a reference human genome sequence that scientists now regularly use to compare with newly generated genome sequences. This reveals genomic changes that have occurred in different populations over time, which provides a more powerful way to decipher the various stories of human origins and ancestry.

Ancient DNA Tells Our Species' History

Nearly 20 years ago, scientists developed techniques for extracting small amounts of DNA from ancient samples, like bones or fur or even soil, and used very sensitive methods for sequencing the extracted DNA. Genomic studies like these have allowed us to examine human genomes from around 500,000 years ago when our ancestors (the species Homo sapiens) were diverging from other similar species, such as Homo neanderthalensis or Neanderthals.

So far, we have learned that Neanderthals took a different path than humans in their migrations around the world, but there are still traces of Neanderthal DNA sequences in our genomes today. These small stretches of DNA may influence traits that have helped people survive in some way, making it more likely to then be passed on to their children. For example, a 2017 study found that some Europeans still carry Neanderthal-like sequences that influence their circadian rhythms, making them more likely to be a morning person or a "night owl." In contrast, some DNA variants might have just happened in one population and not another. The same study found variations in the MC1R gene that lead to red hair were extremely rare or nonexistent in Neanderthals, so that trait seems to be human-specific. As we find better ways to isolate DNA from ancient remains and improve our DNA sequencing technologies, we will learn more about our species' history.

Human Migrations Out of Africa

What happened when humans began to migrate out of Africa and move around the world? Genome sequencing of Africans living in different times - from as long as 6000 years ago to today - has revealed that humans divided into different groups and moved around the world at multiple times. In Southern Africa, local hunter-gatherers and then herders appear to have been replaced by Bantu farmers around 2000 years ago. As humans migrated into Europe, the genomes of different groups also began to retain different variants. One 2008 study looked at about 200,000 specific places in the human genome where people are different from each other, among a collection of Europeans. The patterns of genomic variants among different groups could be used to reproduce the map of Europe with 90 percent accuracy. Even more surprising, when a new European person's genome was analyzed, the researchers could predict where that person was from within a few hundred kilometers. More recent studies in the United States also show that genomic variation coupled with genealogical records can be used to infer birth location quite accurately.

Ancestry and Identity

As we learn more about genomic variation in specific populations and groups, more robust tests are being developed to help you decipher your ancestral origins. But, before you take one, you need to be aware that the results of these tests may alter your perception of your family history and even of yourself. The DNA Discussion Project, started by West Chester University professors Drs. Anita Foeman and Bessie Lawton, aims to encourage greater understanding of the science of genomics, the social construct of race, and the perception of ethnicity. For example, as Drs. Sarah Tishkoff and Carlos Bustamante's research groups showed in 2010, an African American individual in the United States has, on average, about 75-80 percent West African ancestry and about 20-25 percent European ancestry. Students at West Chester shared that while they had always been told that their family had Native American ancestry, the DNA tests revealed this was not the case.

With such ancestry testing, some people have discovered that their ancestral origin is not what they thought, while others have found that close relatives are not who they thought. Some adopted children have used DNA tests to track down their birth parents, or to find previously unknown siblings. Meanwhile, some studies report that, depending on the country, anywhere between 1 percent and 10 percent of children are raised thinking that someone is their biological father when, in fact, that person is not. Ancestry testing can lead to delicate and complex situations, so it is important to think about the potential consequences before using such tests.

Science For Everyone

There are many commercial services that allow you to purchase a genomics-based ancestry test or to explore your family's genealogical history. A quick internet search will reveal many options.

As people have become more proactive in managing their health, personal genomic direct to consumer (DTC) testing has become more popular over the past decade. These tests allow consumers to access information about genetic predispositions and response to chemicals and medications without the involvement of healthcare providers. With the expanding landscape of such testing, the need for provider education and public genetic literacy has become more important than ever.

Typically, these tests use DNA derived from saliva to measure hundreds of thousands of genetic variants and provide individualized reports on genetic predispositions to common conditions, such as Alzheimer’s disease, celiac disease and Parkinson’s disease. Some tests also include information on carrier state for rare genetic conditions such as hereditary hemochromatosis and hereditary thrombophilia.

Although personal genomic tests for disease susceptibilities could help to make decisions about lifestyle choices or inform discussions with providers, they are not diagnostic tests, and cannot be used alone for treatment decisions or other medical interventions (in contrast, for example, to BRCA gene testing for hereditary breast and ovarian cancer).

The pros and cons of personal genomic DTC tests have been discussed for years. We have adopted a cautionary attitude about personal genomic tests. In 2011, we advised consumers to think critically about the health utility of these types of tests, as well as the potential harms and unnecessary follow-up health care costs that could result from testing. In our three-tiered evidence classification of genomic tests, we include personal genomic tests as “tier 3” tests. Such a rating implies that there is no evidence for clinical validity or utility of such applications in healthy individuals in the population. In 2009, on the basis of a scientific workshop, we called for additional research to evaluate the validity and utility of personal genomic tests to improve health and prevent disease. Over the past few years, some of that research has been conducted and published. For the most part, data on personal genomic testing have revealed little or no harms but also little or no health benefits. Also, evidence on the ability of genetic information to change health behavior has been lacking.

With improved technology and plummeting prices in the coming decade, we could see an expansion of DTC testing for personal genomic information. The content of information obtained from such testing will evolve. Nevertheless, both the general public and the health care provider community need to be aware of the potential utility and limitations of such tests. In a 2016 study, a survey of people who underwent personal genomic tests found that most of those tested who shared results with their health care providers were not satisfied by the reaction of their providers. Many providers questioned medical actionability of the test results and showed lack of engagement or interest. In a recent commentary in Nature, Dr Zak Kohane from Harvard University stated that when it comes to personal genomic tests, “we really have a perfect storm of insufficient data and insufficient competence.” Physicians aren’t yet prepared to handle genetic test results of this type and neither is the general public.

While evidence of utility of personal genomic information continues to be collected through ongoing research studies, it is important for professional societies, healthcare organizations, public health agencies and the private sector to improve the level of genomic health literacy of the public. We all need unbiased information to be empowered to make the most informed decisions about genomic and other tests for our own health. Our advice, in 2017, remains the same as in 2011, namely for consumers to think before they spit and rush to do DNA personal genomic testing.

1. How can consumers use information from direct-to-consumer tests?

While direct-to-consumer tests can lead to consumers becoming more engaged in their overall health and lifestyle decisions, results from direct-to-consumer tests should not be the sole basis of any type of medical decision making as these tests provide only one layer of a bigger picture. Therefore, results from direct-to-consumer tests should always be discussed with your health care provider. In addition, these tests are not a substitute for visits to a health care provider for recommended screenings or appropriate follow-up and should not be used to determine any treatments.

2. Are direct-to-consumer tests accurate?

No test is 100% accurate. Some tests may be wrong due to an error in the test, and some results may be wrong due to an incorrect interpretation of the meaning of the result.

3. I received opposite or different results from two different companies. Why?

Different companies may test for different sets of variants, much like a store may offer different brands of products. One direct-to-consumer test company may look for one set of variants linked to a disease or condition, while a different test company may look at a different set. Additionally, direct-to-consumer tests may disagree on the interpretation on whether a variant is disease-causing or not.

Experts don't always agree and the reasons for this vary. For example, one direct-to-consumer company may have private information about a variant based on their test population that another test company does not have. Another direct-to-consumer company may use different criteria when determining whether a variant is linked to a disease or condition. It is important that consumers understand what is being tested when they receive results from different companies and whether they are testing the same genetic variant.

For direct-to-consumer genetic tests, you may consider speaking with a genetic counselor, board-certified medical geneticist, or other equivalent health care provider. If you have concerns about a particular test result received from a direct-to-consumer test company, you can report problems directly to the FDA through MedWatch, the FDA's voluntary reporting program.

4. If my direct-to-consumer test is negative, does that mean that I will not develop that condition?

Not necessarily. Many diseases or conditions may be caused by a number of factors including genetics, lifestyle, and environmental factors. Additionally, not all genetic tests are looking for all of the variants that can contribute to disease development. For example, some tests might only look for a couple of variants, even though hundreds or thousands of variants can contribute to disease development. Therefore, it is especially important to continue routine medical preventive care or recommended screenings even if you receive a negative genetic direct-to-consumer test result. Consumers should consult with their health care provider about the right steps to take following receiving results from any direct-to-consumer test.

5. If my direct-to-consumer Genetic Health Risk test is positive, what does that mean?

A positive direct-to-consumer genetic health risk test does not indicate that an individual will develop a given disease or a condition. Many diseases or conditions may be caused by several factors including genetics, lifestyle, and environmental factors. However, consumers should consult with their health care provider about the right steps to take following receiving results, including getting confirmatory genetic testing, if applicable.

6. My direct-to-consumer test indicates that I'm at risk for a given health condition, but my sibling isn't. Why is that?

People inherit half of their genes from each of their parents – giving them a completely new and unique set. Siblings may inherit different genes from each of their parents and are therefore not genetically identical (unless they are identical twins). In this situation, you may have inherited a gene with a variant putting you at risk for a disease or condition from one of your parents, while your sibling did not.