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A Closer Look at Direct-to-Consumer Genetic Testing

GEC-KO logoDirect-to-consumer genetic testing (DTC-GT) is over-the-counter genetic testing available online to consumers through private companies. In general, consumers purchase a package, receive a spit-kit in the mail and return a saliva sample for analysis. With the rapid pace of genomic technology, decreasing cost and a significant increase in consumer awareness, purchase of these kits is expected to increase.

Generally, results report an individual’s risk to develop a medical condition as being below average/low, average/general population, and above average/ high based on genome wide association studies (GWAS). GWAS are case-control studies which examine many common variations in our genetic code (single nucleotide polymorphisms [SNPs]). They compare large groups of individuals (unaffected controls versus individuals with symptoms of a specific disease or those experiencing a particular medication response) in an attempt to distinguish between non-harmful changes in the DNA code and pathogenic, disease causing/predisposing changes. SNPs (pronounced ‘snips’) are the most common type of genetic variation. Each SNP represents a difference in a single DNA building block, a nucleotide. SNPs occur normally in an individual’s genome about once in every 300 nucleotides, and so there are about 10 million SNPs in the human genome.

Results from DTC-GT may provide medically useful information for consumers and potentially provide support and motivation for lifestyle changes (e.g. weight loss, smoking cessation) or even more vigilant surveillance (e.g. breast cancer screening), reveal carrier status of single gene conditions (e.g. cystic fibrosis), effectiveness and side-effect risk of certain pharmaceuticals, in addition to medically irrelevant information (e.g. curly hair).

DTC-GT results should be interpreted with caution as factors such as age, family history, lifestyle (e.g. smoking, obesity) and other environmental factors are not taken into account but contribute to developing common complex diseases (e.g. diabetes, cardiovascular disease). Family health history-based risk assessment is still the gold standard in initial assessment for heritable conditions.

Numerous professional societies express concern about how DTC-GT is marketed to consumers, what and how information is provided and the lack of genetic counselling. In Canada diagnostic laboratories are provincially regulated. At the time of writing, no DTC-GT is operating under approved provincial regulation, although some may meet USA federal standards (e.g. Clinical Laboratory Improvement Amendments, CLIA). Companies that are not regulated could have staff performance, test analysis and interpretation of results that may not be certified or licensed by any appropriate governing body.

Additionally, privacy is a major concern. DTC-GT companies have self-imposed policies that claim a consumer’s genetic information will not be shared, although there is no regulation to dictate what happens if/when a company is sold or goes out of business. Patients should be advised to look into the privacy policy prior to purchasing DTC-GT.

Are your patients asking about DTC-GT?

Do you want more information to have more informed conversations with your patients? Visit the GEC-KO website for more information and references in our GEC-KO on the run and our education module with case examples.

About GEC-KO

Genetics Education Canada – Knowledge Organization (GEC-KO) is a genetics education program funded by the Children’s Hospital of Eastern Ontario (CHEO) with in-kind support from Mount Sinai Hospital in Toronto. GEC-KO is dedicated to the development, collection, dissemination and evaluation of genetics educational materials for healthcare providers, especially primary care providers. The GEC-KO website contains educational resources and point of care tools designed for primary care providers and intended to facilitate integration of genomic medicine into practice. Additionally, at you can identify your nearest genetics centre and find the information you need to connect with your local genetics specialist and laboratory.

Article written by: Shawna Morrison for Genetics Education Canada – Knowledge Organization (GEC-KO)

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