What Your Whole Genome Can and Can't Tell You

Last Thursday, Veritas Genetics announced it will make available your entire genetic sequence for just $999. That's all of your body's instructions for making and running the machine known as you for roughly the price of a big-screen TV.

The sequencing, which will be available for order on March 30, needs to be requested through a physician. Veritas said you will also receive interpretation and on-demand genetic counseling -- just as important as the sequence itself. After all, without this analysis, you'd be staring at your specific combination of 6 billion or so As, Gs, Cs and Ts with no way to decode it.

While Veritas isn't the first company to provide you with access to your DNA, it's the first to offer your whole genome for that low a price. A company called Sure Genomics, for example, launched a whole genome service last month, costing $2,500 plus $150 annually for biannual updated analyses that will take into account newly found genetic markers.

Given the complexity of the possible results, it will be interesting to see what you get for such a low price.

With Genetic Sequencing, Is Less More?

Whole genome sequencing is different than what the company 23andMe offers, for as little as $199. Rather than looking at your entire genome, 23andMe searches for already known genetic variations, like those for cystic fibrosis, sickle cell anemia, and other diseases and traits.

Because 23andMe only looks for the  parts of your DNA known to be associated with certain traits or diseases, it can’t report on variations that are present but have yet to be determined as significant. Or on rare variants that they know what effect they have but do not test for.

Remember how your mom told  you you're "special." Well, that's technically true, because everyone’s DNA is unique.

But it also means scientists trying to interpret vast stretches of your genetic code is like Egyptologists staring at hieroglyphics without the benefit of the Rosetta Stone. So even though your entire genome has the potential to one day tell you a whole lot about yourself, currently it's not saying much. And anyone looking at it won't know how or whether the majority of combinations in your genetic code determine your health and other traits.

For example, if a unique sequence falls within a gene implicated in a disease, then you may or may not be at a higher risk for that disease. Sometimes scientists can make a reasonable prediction, but often they can’t. Now imagine these types of unknowns strewn throughout your genome.

But this will not always be the case. As scientists learn more and more about what different parts of the human genome can tell us, your own sequence will become more and more communicative, so to speak. Meaning one day, that information could be found to impact your health.

You Need Coverage

If you do choose to spend more money to explore the unknown reaches of your genome, you want to make sure that data is high quality. Good quality genomes don’t contain a lot of mistakes, and they aren’t missing big sections.

The key thing to look for is something called "coverage."

Basically, coverage is how many times on average your genome has been read. One rule of thumb: If a whole genome sequence (WGS) is going to be used to predict individual characteristics, it should be read a bare minimum of 30 times.

Dr. Michael Snyder, chair of the Department of Genetics at Stanford University, says even more is better. "I would do at least 60X and even that will not give adequate coverage in a lot of regions."

Why do scientists need to read the same DNA over and over again? Mainly because  while new technologies have made sequencing much cheaper, they have also made it vulnerable to a greater number of mistakes. Scientists now need a lot of reads to ensure the sequence is correct.

Another reason so many reads are required is that some parts of the genome just don’t sequence very well. You need to do a lot of sequencing to get these regions to appear in the data.

More than DNA

Of course with Veritas and other services that provide you with your entire genome, you are paying for more than your genetic code. You are also paying for the interpretation and the counseling that comes with your results.

How valuable that is to you will depend on which results the company interprets, how much counseling it will offer, and, finally, how you will respond to the data. Handled right, information about your genetic predispositions can be extremely helpful. But handled poorly, it can be confusing, worrying, and perhaps lead to unintended consequences.

They say a little information can be dangerous. But too much can be overwhelming.