Direct-to-Consumer Genetic Testing: A Primary Care Perspective

Last year was the 10th anniversary of the completion of the Human Genome Project (HGP). We are in exciting times when monumental strides have been made in understanding human genetics.

The HGP has taught us that the human DNA consists of 3.2 billion nucleotide base pairs, and the human genome sequence is 99.9% same in all people.

In the 1990’s, there were genetics tests for approximately 100 diseases and now, there is testing for almost 3000 diseases.  Whole genome sequencing is available for less than $10,000, and anyone can order genetic testing online for less than $100.

With this direct-to-consumer genetic testing (DTCGT) readily accessible to anyone, we need to look at: What is DTCGT? What does it tell us? What does this mean for the consumer and their primary care physician?

DTCGT is a commercially available screening of a person’s DNA/genome for genetic variations that have reported associations with diseases or risks of diseases.  In May 2010, an attempt was made by Pathway Genomics to market the screening at Walgreens pharmacies across the nation; however, this was suspended after a statement by the Federal Drug Administration.

Now, a kit can be ordered from 20 available companies online and mailed directly to the consumer.  The consumer then obtains a cheek swab or saliva sample and mails it back to the company. A few weeks later, the results are provided. Most of the provided test results are predictive rather than diagnostic.

These predictive tests are based on genetic variations, predominately single nucleotide polymorphisms (SNPs) that are associated with certain diseases. The results offer susceptibilities or risks of a person developing common diseases such as diabetes, heart disease, or prostate cancer.

These relative risks or odds ratios are derived from case-control studies, called Genome Wide Association Studies (GWAS), which compare DNA of the people with the disease to those without the disease. SNPs are identified that are more common in individuals with the disease and a relative risk is assigned. Based on these SNPs that are identified in the consumers DNA, the report provides them the possibility of developing the disease in the future.

Although the testing for the genetic variations themselves is highly sensitive and specific, there are many aspects that are unknown. First, there needs to be standardization in the genetic testing and the laboratories.

Different companies use different SNPs, thus different risks can be obtained for the same person depending on which DTCGT company he or she used. Most of the laboratories in the companies are Clinical Laboratory Improvement Amendment (CLIA) accredited, but some are not.  Secondly, we are unsure how useful and beneficial the DTCGT results are to the consumers.

Bloss et al found no measureable short-term changes in psychological health, diet and exercise behavior, or use of screening tests for 6 months after a cohort of patients chose to undergo consumer genetic testing. Lastly, ethical considerations, such as privacy and confidentiality issues, should be taken seriously when genetic testing is widely available.

The Genetic Information Non-discrimination Act (GINA), signed in 2008, offers protection such that health insurers cannot use genetic information to set eligibility requirements and establish premiums or contribution amounts. In addition, employers cannot use genetic information in decisions about hiring, firing, job assignments, or promotions. However, GINA does not protect against or apply to life, disability, or long-term-care insurers.

When a consumer does decide to get genetic testing online, to whom will they turn to get questions answered?  According to McGuire et al who studied attitudes of Facebook users, 78% of those who considered DTCGT would ask their physician for help interpreting the results, and 61% of all responders believe physicians have a professional obligation to help interpret results.

However, most primary care physicians are not equipped to answer questions about online genetic testing, much less understand the information themselves. Our future physicians are in agreement as demonstrated by Ormond et al who surveyed first year medical students and graduate students both, before and after, a core genetics course.

Eighty-seven percent of the students agreed or strongly agreed physicians have a responsibility to help patients interpret results of personal genetic testing, but less than a third felt that physicians have the knowledge to help interpret results.

Understanding genetics will provide us with the ability to individualize care for our patients. We may be able to prevent chronic diseases before they take a foothold or provide tailored medications without the risk of side effects or adverse events.

Therefore, in this age where genetics research and knowledge is growing exponentially in leaps and bounds, we need to advocate for education to benefit our consumers and our physicians.

Emily Wang