What Is Direct-to-Consumer Genetic Testing (DTC GT)?

The DTC GT market has expanded rapidly over the last 20 years as the costs of genetic testing and sequencing have fallen, and was estimated to be worth USD 1.24 billion in 2019. DTC GT involves the use of genetic tests that are marketed directly to consumers without a need for the involvement of a healthcare professional. The tests can be ordered online or by post, and the consumer completes the test at home (usually by rubbing a swab over the inside of their cheek or providing a saliva sample) before sending it away for analysis. The results are then sent by post, given via a telephone call, or accessed via a secure website or app.

How Does DTC GT Work?

Your DNA (deoxyribonucleic acid) carries the genetic information for the growth, development, and function of your body. It is made up of two long chains of units called “nucleotides” that coil around each other to form a double helix. The term “gene” describes a short section of DNA, whereas the term “genome” describes the complete set of genetic material in a cell or whole organism. Some genes have specific functions, like coding for proteins, but others don’t. The human genome is currently estimated to be made up of around 20,500 protein-coding genes, and the number of non-protein-coding genes may be greater.

Genetic testing looks for variations in the DNA sequences that make up genes. Gene variations can be inherited or can occur if a permanent change to the DNA sequence happens during a person’s lifetime. There are different types of variations that can occur in DNA, including the replacement of one nucleotide with another (known as a “substitution”) and the deletion and/or insertion of at least one nucleotide. If a substitution is found in at least 1% of the global population it is classified as a SNP (this stands for “single-nucleotide polymorphism” and is pronounced “snip”). Over 600 million SNPs have been reported to date, and although most SNPs have no effect on peoples’ health, some are associated with the risk of developing disease.

Many DTC GT test companies use a method called SNP-chip genotyping, which looks for the presence or absence of SNPs and nucleotide insertions and deletions. Other DTC GT companies use genome sequencing, which sequences a person’s entire genetic code and identifies variants that are present. Some companies provide the consumer with “raw”, uninterpreted data that needs to be interpreted by a third party, whereas others provide some form of health information based on their interpretation of the results. For example, some may combine results relating to a group of variants to place someone in a risk category while others notify the consumer if they have tested positive for specific variants implicated in a disease or response to a drug.

Why Do People Opt for DTC GT?

Some of the main advantages of DTC GT are that it is often less expensive than testing conducted via private healthcare providers, and it doesn’t involve the approval or involvement of a healthcare professional or insurance provider. The results are also delivered directly to the consumer so they don’t appear on the person’s medical or insurance records.

The process of collecting a sample for testing is usually quick, non-invasive, and can be done in the user’s home. Many users opt for DTC GT in the hope that they will get clear information about their future health and may feel that they are being proactive about their wellbeing. Some may feel that they are contributing to knowledge that may help others through future research. Consumers may also be curious to understand more about their ancestry.

What Are the Potential Disadvantages of DTC GT?

DTC GT often only takes a superficial look at particular genes and isn’t designed to diagnose genetic conditions. DTC GT is often good at detecting common genetic variants, but if a variant is detected that is rare, the result can often be a false positive (an error where the test result is positive but should actually be negative). This can be extremely worrying for the consumer if they think they have been identified as having a disease-linked genetic variation.

Equally, a test result could be a false negative (an error where the test result is negative but should actually be positive), and receiving a true negative result doesn’t necessarily mean there is no chance of developing that condition. It may just be that the company used doesn’t test the full set of possible genes that can be tested for that condition, and new variants and their implications are also being discovered all the time. Some companies offer someone to talk to about the results obtained, but consumers may struggle to access qualified advice if they receive a result that causes them to worry. Results can also be obtained that affect the whole family or demonstrate that family relationships are different to what is expected.

It is important that consumers understand the limitations of genetic testing. Finding a disease-linked genetic variation doesn’t automatically mean that someone will go on to develop that disease. A person’s health depends on a wide range of factors, not just their genetics. Environmental factors (such as exposure to harmful substances or access to healthcare), lifestyle choices and family history all play a role, and the health advice given to a person is unlikely to change as a result of them undertaking DTC GT.

Consumers also need to bear in mind that there may be implications regarding their health insurance if they undertake DTC GT and get a result that suggests genetic susceptibility to a disease. Some companies might not be clinically accredited (so the results might not credible or be backed by robust data) and there is currently little regulation of companies. As a result, the onus is on the consumer to assess the quality of the service before going ahead with testing. There may be other issues concerning whether the consumer is asked to provide proper informed consent, and some companies might collect, store, sell, or undertake research using the genetic data that they obtain (secondary data use is defined as the use of consumer data for purposes other than producing a report on the consumer’s health and/or ancestry). Law enforcement agencies may also request access to the information that the companies hold during their investigations. Risks associated with the use of secondary data and the reidentification of individuals from their data include civil lawsuits, forensic investigations, problems with immigration, discrimination, and the allocation of health resources.

What Did This Study Show?

The authors used semi-structured interviews to investigate the knowledge of and attitudes to DTC GT of a group of 20 people in the USA who self-identified as Black or African-American. In particular, the participants were asked about their motivations for testing and their views on secondary data use and privacy. The study showed that the participants were generally positive about DTC GT, but had little concrete knowledge about secondary data use practices by DTC GT companies. Few had read the company privacy policies in detail, and most expressed concerns about the privacy of their information. One-half of the group surveyed did not know whether they had the option to opt out of secondary data use by the DTC GT company. Most participants also expressed the opinion that informed consent, following the provision of clear information prior to testing about potential future uses of data, should be required for any secondary use, with the option to opt out of any and all potential future uses. The general view was that DTC GT companies need to improve transparency. In addition, when the authors compared their findings with those of a previous study, which had surveyed European-Americans who had undergone DTC GT, they found that there were differences in themes such as a moral duty to participate in research to redress historical underrepresentation in genetic studies, community considerations, and concerns about racial inequality.

Take-Home Message

DTC GT companies can do more to draw on the consumer experience and improve their consent processes and information, particularly regarding the clarity and accessibility of the language used in their privacy policies. However, the onus remains on the consumer to be informed. People considering DTC GT should look for balanced advice from reputable organisations before making a decision, and should speak to their healthcare professional if they have concerns regarding the possibility of a genetic condition in their family. If they decide to go ahead with DTC GT, consumers should check the privacy policy carefully and be clear on what help the company will provide regarding the interpretation of results.