Its becoming fashionable to order yourself a Genetic Test by mail. You may have health issues you’d like to know more about, you may simply be inquisitive about your ancestry or you might want to determine if you’re at risk from certain types of cancer and other diseases. Whatever your reason, nowadays you’re spoilt for choice and the companies offering Direct to Consumer (DTC) Genetic tests are popping up everywhere.
So what exactly do these tests offer? What can you test for and how reliable are the results? Are there any pitfalls and warning signs that suggest you should be wary of a service and what are the risks of your genetic data being shared? Lets start with a definition of DTC Genetic testing and then first address what these tests cannot do.
What is DTC Genetic Testing?
Most of the time, genetic testing is done through healthcare providers such as physicians, nurse practitioners, and genetic counselors. Healthcare providers determine which test is needed, order the test from a laboratory, collect and send the DNA sample, interpret the test results, and share the results with the patient.
Direct-to-consumer genetic testing is different: these genetic tests are marketed directly to customers via television, print media, or the Internet, and the tests can be bought online or in stores. Customers send the company a DNA sample and receive their results directly from a secure website or in a written report.
Direct-to-consumer genetic testing provides people access to certain of their genetic information without necessarily involving a healthcare provider or health insurance company in the process.
Dozens of companies currently offer these tests for a variety of purposes. The most popular tests use genetic variations to make predictions about health, provide information about common traits, and offer clues about a person’s ancestry. The number of companies is growing, along with the range of health conditions and traits covered by these tests.
Because there is currently little regulation of direct-to-consumer genetic testing services, it is important to assess the quality of available services before pursuing any testing.
Will a DTC Genetic test tell me if I’m likely to get cancer?
While a direct-to-consumer genetic test can estimate your risk, it cannot tell you for certain whether you will or will not develop certain forms of cancer. Many other factors, including gender, age, diet and exercise, ethnic background, a history of previous cancer, hormonal and reproductive factors, and family history also contribute to a person’s overall cancer risk.
The U.S. Food and Drug Administration (FDA) has allowed at least one direct-to-consumer genetic testing company, 23andMe, to offer a test for cancer risk. The test looks for three specific variations in two genes: BRCA1 and BRCA2. These variations are associated with an increased risk of breast cancer, ovarian cancer, and potentially other forms of cancer in people of Ashkenazi (eastern European) Jewish ancestry.
Researchers estimate that 5 to 10 percent of all cancers run in families. Some of these cancers are associated with inherited mutations in particular genes, such as BRCA1 or BRCA2. More than 1,000 variations in each of these genes have been associated with an increased risk of cancer. However, the FDA-approved direct-to-consumer genetic test analyzes only three of these variations. The variations included in the test are much more common in people of Ashkenazi Jewish background than in people of other ethnicities, so if you are not of Ashkenazi Jewish heritage, the results may not be useful to you.
Because the variants included in the test are uncommon, most people will have a negative result. A negative result does not mean that you will never get cancer. Similarly, a positive result (one that indicates a cancer-related genetic variation) does not mean that you will definitely develop cancer.
Can a DTC genetic test tell if I will develop Alzheimer disease?
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.
The U.S. Food and Drug Administration (FDA) has allowed at least one direct-to-consumer genetic testing company, 23andMe, to offer a test for Alzheimer disease risk. The test analyzes a gene called APOE. Certain variations in this gene are associated with the likelihood of developing late-onset Alzheimer disease (the most common form of the condition, which begins after age 65).
Specifically, the test allows you to find out how many copies (zero, one, or two) you have of a version of the gene called the e4 allele. People who have zero copies of the e4 allele have the same risk of late-onset Alzheimer disease as the general population. The risk increases with the number of copies of the e4 allele, so people with one copy have an increased chance of developing the disease, and people with two copies have an even greater risk.
However, many people who have one or two copies of the e4 allele never develop Alzheimer disease, and many people with no copies of this allele ultimately get the disease.
Variations in the APOE gene are among many factors that influence a person’s overall risk of developing Alzheimer disease. Variations in many other genes, which are not reported in the FDA-approved direct-to-consumer genetic test, also contribute to disease risk. Additionally, there are risk factors for Alzheimer disease that have yet to be discovered.
The APOE e4 allele represents only one piece of your overall Alzheimer disease risk. It is not definitive, but one of many possible indicators.
Can the results of DTC genetic testing affect my ability to get insurance?
A federal law passed in 2008 called the Genetic Information Nondiscrimination Act (GINA) made it illegal for health insurance providers in the United States to use genetic information in decisions about a person’s health insurance eligibility or coverage. That however does not prevent Insurance companies from requesting this data as part of your medical history and GINA does not apply when an employer has fewer than 15 employees.
GINA does not apply to other forms of insurance, such as disability insurance, long-term care insurance, or life insurance. Companies that offer these policies have the right to request medical information, including the results of any genetic testing, when making decisions about coverage and rates. You should weigh the possible benefits and risks, including potential impacts on insurance eligibility and coverage, before you start the testing process.
What DTC Genetic tests are available?
With so many companies offering direct-to-consumer genetic testing, 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 are very specific (paternity tests), while other services provide a broad range of health, ancestry, and lifestyle information.
Disease risk and health
The results of these tests estimate your genetic risk of developing several common diseases, such as celiac disease, Parkinson disease, and Alzheimer 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 one copy of a gene mutation that, when present in two copies, causes a genetic disorder.
The tests may also look for genetic variations related to other health-related traits, such as weight and metabolism (how a person’s body converts the nutrients from food into energy).
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.
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). The results of direct-to-consumer kinship tests, including paternity tests, are usually not admissible in a court of law.
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 test, find out what kinds of health, ancestry, or other information will be reported to you. 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.
A more detailed look at Genetic Ancestry Testing
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, passed exclusively from father to son, can be used to explore ancestry in the direct male line. Y chromosome testing can only be done on males, because females do not have a Y chromosome. However, women interested in this type of genetic testing sometimes recruit a male relative to have the test done. Because the Y chromosome is passed on in the same pattern as are family names 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, which is passed on from their mothers, so this type of testing can be used by either sex. 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 variations (single nucleotide polymorphisms or SNPs) across a person’s entire genome. The results are compared with those of others who have taken the tests 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.
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 ethnic background of an individual.
Genetic ancestry testing has a number of limitations. Test providers compare individuals’ test results to different databases of previous tests, so ethnicity estimates may not be consistent from one provider to another. 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.
Selecting a company for your DTC Genetic Test
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? 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.
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.