23andMe: my foray into personalized genomics

Just over a year ago the personalized genomics company 23andMe dropped the price of their genetics testing service to $99. My family and I decided to try their product after hearing a few stories of people who gained valuable health information as a result of the service. As an added bonus for my dad, a genealogy buff, the service includes ancestry tracing and an option to ‘share genomes’ with potential distant relatives.

23andMe takes a sample of your DNA (from spit) and analyzes a set of markers at thousands of locations across your genome called single nucleotide polymorphisms (SNPs). Since this analysis uses a small plastic chip coated with probes to query these sites, this genome-wide genotyping analysis is called a “SNP-chip.” Basically it asks which of the letters that make up the genetic code, A, T, C, or G, occur at a particular spot in your DNA, and then repeats this question 32,000 times. SNPs are essentially little genetic flag posts. The presence of a certain SNP (an A at a site that usually carries a G) can indicate a predisposition for heart disease, or may be associated with curly hair.

We gathered around the table and spit into our little sample collection tubes, registered online, sent the samples off in the mail, and waited.

Two of us opted in to their ‘contribution to research’ and began filling in prescription histories, general health background information, and answering questions such as whether or not our mother smoked while pregnant with us. Two of us opted to not share any further information at this time.

These answers, along with our self-reported medical history and drug responsiveness are entered into the 23andMe data crunchers to be processed in studies called Genome Wide Association Studies (GWAS). GWAS studies look for correlations between SNPs and a particular trait such as responsiveness to a drug, ability to curl your tongue or wiggle your ears, or the likelihood of developing breast cancer.

Within one to two months of sending our samples in, our data was processed and uploaded, and we could read through a carefully curated list of genetic risks, carrier status (diseases we could potentially pass on to our children), fun traits, and ancestry information.

The test is well worth the $99 just for the ancestry and fun trait information. For those who know what they’re doing with the raw SNP data, these files are also made available. The selling point, though, was the genetic risk and carrier status information. I have a fairly complete medical history from almost all of my immediate relatives going back at least two generations, so I had a pretty solid idea for what to expect for the most part, but having a gene-based confirmation of those assumptions was massively relieving. Further, I identified a trait or two which I deemed actionable, and I feel confident that the measures I’m taking post 23andMe revelation are making me healthier and happier.

It’s important to keep three things in mind, though, when going through this genetic data.
1. There are always error rates associated with these tests. If I were to send in my spit four more times I may get slightly different genotypes for any given SNP in each of those samples.
2. This is a SNP-Chip and associated GWAS studies, not sequencing and molecular mechanism. SNPs are often simply associated with functional regions of genetic code, and may not actually indicate an error in a functional gene. And GWAS studies are correlations, and don’t always indicate causation. Take these annotations with a grain of salt. An exact DNA sequence for your entire genome would be far more informative, and is probably on the way. Even so, for most of these disease correlations, vague association/correlation is as good as it gets at this point in the game.
3. These are DNA samples from your spit. No amount of habit changing or exercise will change these results, but they’re also not written in stone. You have the same DNA in every one of your cells, but a skin cell is different from a liver cell or a brain cell. There are many layers of regulation governing which genes get turned on when and where. Just because you have a gene associated with a predisposition to high blood pressure doesn’t mean you’re doomed to develop high blood pressure. This just means that perhaps you should consider a diet lower in sodium and a more active lifestyle.

23andMe makes a significant effort at educating their clients on exactly what they’re purchasing with the service, and offers loads of mini biology lessons. However, with direct-to-consumer genotyping making such intimate health details available without a physician intermediary the FDA was bound to get involved sooner or later. Since people may start making medical choices based on their data, the FDA ordered a cease and desist while it investigates regulating the genetics test as a medical device. For the time being, the health and disease risk results are shut down to newcomers on the site, but the genetic trait and ancestry information is still available.


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