This article in Wired explains how there is a lot more to sequencing the whole genome than just 23 genes. The cost of full sequencing has dropped to $1000, which is considered an enormous breakthrough, and it is expected to continue to fall. One company is even offering a $200 black Friday special even though they admit it is a loss leader.

Today, slightly more than a million people have had their whole genomes sequenced. Compare that to the 17 million estimated to have had their DNA analyzed with direct-to-consumer tests sold by 23andMe and Ancestry. They use a technology called genotyping, which takes about a million snapshots of a person’s genome. That might sound like a lot, but it’s really less than 1 percent of the full picture. Genotyping targets short strings of DNA that scientists already know have a strong association with a given trait. So say, for example, scientists discover a new gene that increases your risk of developing brain cancer. If that gene is not one that 23andMe looks at (because how would it know to look if the gene hasn’t been discovered yet), then you’d have to get tested all over again to learn more about your brain cancer risk. Whole genome data on the other hand, once you have it, can be queried with computer algorithms whenever a new genetic discovery gets made.

Here’s a good example of just how much more info is in a whole genome: Earlier this year, 23andMe got FDA approval to give consumers information about their BRCA1 and BRCA2 genes. More than 1,000 mutations in these genes are known to increase women’s chances of breast and ovarian cancers by as much as 75 and 50 percent, respectively. 23andMe’s test picks up the three BRCA mutations most commonly found in individuals of Ashkenazi Jewish descent, and geneticists have voiced concern that the results could leave people with a false sense of security. Veritas’ tests, on the other hand, scan for all of them and, according to the company, turn up five to seven variants of varying concern in those two genes for the average customer.