Advising patients interested in direct-to-consumer genetic testing
Direct-to-consumer genetic testing generally involves patients purchasing tests online; prices are reported to vary
from $100 to $1000.4 This is a rapidly expanding area of commercial interest. It has been estimated that by 2018 the global
direct-to-consumer genetic testing market will be worth more than NZ$300 million.4 However, whether this market will be
able to provide health-related information in the future is currently uncertain. In late 2013, the U.S. Federal Drug Administration
(FDA) contacted the major supplier of direct-to-consumer genetic testing and ordered them to “immediately discontinue
marketing” their testing kit and personal genome services. This was due to concerns about how information provided by
testing kits might be interpreted by consumers.5 In order to comply with the FDA request direct-to-consumer genetic testing
companies in the United States must not provide consumers with genetic interpretations that relate to health.
The quality of any information provided by direct-to-consumer genetic testing can vary enormously. Therefore health
professionals can recommend caution to patients who are considering purchasing private testing, focusing instead upon
the specific health concerns the patient has, and providing evidence-based advice. For example, a patient who is concerned
about colorectal cancer can be advised to eat a healthy diet, e.g. that includes fish as a source of protein, nuts, seeds
and olives as sources of fats, and legumes and fruits for carbohydrates. However, if a patient has purchased a genetic
test, and asks for assistance in interpreting the results, the information the test provides should not be dismissed.
The majority of people who purchase direct-to-consumer genetic tests do not have a known family history of a specific
disease; the test is purchased out of simple curiosity. Results from tests requested for these purposes are unlikely to
be clinically useful as there are many factors affecting phenotypes such as cardiovascular disease or diabetes. Any decision
to further investigate the patient’s health should be evidence-based.
A second reason that people purchase direct-to-consumer genetic testing is to discover information about their ancestry.
These tests use maternal mitochondrial DNA and Y chromosome DNA to provide continental and regional information about
ancestors. These tests can even tell consumers what percentage of their DNA is shared with Neanderthal.4 However, this
sort of ancestry testing has no clinical use.
Some people may purchase direct-to-consumer genetic testing to request pre-symptomatic testing for susceptibility genes
with a high predictive value, e.g. BRCA1 and BRCA2, or to determine carrier status of autosomal recessive conditions such
as cystic fibrosis. Patients who present to general practice with results of genetic testing that suggest the presence
of a known genetically inherited disorder should be referred to GHSNZ for counselling. When discussing test results that
are negative for a specific condition, it is important to point out to patients the possibility of a false negative result
where only a few mutations have been tested.
Before purchasing direct-to-consumer testing, consumers should be aware that there are currently no commercially available
genetic tests that have been approved by the FDA and therefore their accuracy and reliability is not known. In New Zealand,
people who have undergone genetic testing are also required to disclose this information if they purchase new health or
life insurance policies. Furthermore, a lack of regulatory control concerning the use of genetic information collected
by commercial entities means that it is uncertain what happens to this information if companies go bankrupt.4
It is important to advise patients that are considering purchasing genetic testing that they will also, in effect, be
testing their family members. It is possible that family relationships can be harmed if genetic information is not accompanied
by appropriate counselling. The results of genetic testing can also have lasting effects on generations to come. Consultation
with other family members before purchasing direct-to-consumer genetic testing should be strongly advised.