Direct to Consumer Genetic Testing: Interesting but Accurate?

Curious if you are a carrier of Tay-Sachs?  Have you ever questioned your potential sensitivity to Warfarin?  Maybe you just want to know if you are at risk for developing breast cancer or type 2 diabetes.  Good news- genetic testing is currently available for you and your patients.  Just purchase online for $99, send in a little spit and the results of your decoded genome will arrive in your inbox within 2-3 weeks.

Direct-to-consumer genetic testing, genetic tests marketed directly to the consumer rather than through health care providers, are becoming more and more prevalent.  Seemingly innocent (who isn't curious about their genetic make-up?), these genetic test kits available for purchase online are marketed like a mini at-home science project.  Unfortunately, they carry larger implications, and may not be all that accurate.

What can consumers discover about their genome with at-home genetic testing?

The most commonly offered genetic testing services for consumers are DNA paternity tests.  The internet is littered with offerings for these kits.  In fact, you can even purchase a paternity test at your local Walgreens.  Aside from identifying familial connections, available at-home DNA tests also examine ancestry (you could be related to a celeb, or maybe you have a larger percentage of neanderthal than the average modern day human), disease risk (you may be genetically prone to developing Dupuytren's Disease), carrier status (you could pass on Maple Syrup Urine Disease to your children), drug response (how much Warfarin will you need to take when you develop a fib?) and traits (I know you have always been curious about your leprosy susceptibility). 

What are the positives and negatives of knowing your genetic code?

The benefit of genomic knowledge is simple.  If you know you are at high risk for developing a certain medical condition, you can work to prevent it.  Individuals with elevated risk for Type 2 Diabetes, for example may be motivated to eat a healthy diet and exercise in order to prevent developing this disease.  Women at increased risk for breast cancer may be more likely to complete recommended screenings.  Knowledge of carrier status can also help couples decide whether to have children.  If both members of a couple are carriers for a certain developmental abnormality, they may wish to make the decision not to risk having children with certain genetic problems. 

The negative aspects of genetic testing are a bit more complex.  Emotionally, genetic testing can take a toll.  Many diseases can be tested for which there is no cure.  Imagine living with the knowledge you are at increased risk for Alzheimer's Disease, Parkinson's Disease or certain types of aggressive cancer.  Genetic knowledge can become a burden to those predispositioned to certain conditions.

Are at-home genetic testing kits accurate?

Naturally, I assumed genetic tests were accurate- I mean, how can you mess up DNA?  Then I read this quote from geneticist Daniel MacArthur.  "Genetics currently sucks at predicting the types of diseases that will kill most of the people in this room" he said at a recent genetics conference. 

Although a certain predisposition or medical condition is written into your genetic code, scientists and medical professionals cannot be sure it will manifest itself.  For example, only 1 percent of individuals homozygous (with two gene copies) for hemochromatosis actually have the disease.  Other genes are likely counteracting the effect of these genetic variants allowing them to live a disease-free life.  Knowledge of one's genetic make-up, such as breast cancer risk, may lead to an individual electing invasive medical treatment, such as a double mastectomy, for a disease they will never actually develop.

Genetics is so complex that even individuals who carry certain genes or whose genomes indicate they should suffer from certain medical conditions may never develop these problems.  Other areas of our genome compensate allowing most of us to live healthy, or at least genetically unpredictable lives. 

Should you consider genetic testing personally?  Recommend it to your patients?

Before I read Daniel MacArthur's quote about how "genetics sucks", I was considering forking over $99 to 23andMe for my own personal genetic info.  I was lobbying even harder for my husband to do it instead so I didn't have to be burdened by knowledge of my own genetic code.  Unfortunately, he refused.  It seems that knowing one's genetic make-up carries more burden than benefit.  The benefit of knowing your disease predisposition is outweighed by the fact that often diseases expressed genetically don't manifest themselves on a larger, practical scale. 

If you are curious about your own genome and are informed about the risks, go ahead and send off your spit.  But, I wouldn't formally recommend direct-to-consumer genetic testing to your patients. 

OK...I know, despite my recommendation against personal genetic testing you are still interested.  Or, maybe you need a last minute Christmas gift for your quirky uncle.  Here is a list of websites offering direct-to-consumer genetic testing:

23 and Me

deCODEme

MySuport360 (Cancer Risk)

The Genographic Project (Ancestry)

GFI Lab (Paternity and Relational)