Your genome, the strands of DNA in the cells of your body, contains more than 3 billion base pairs—chemical bonds that act like letters of code. Amazingly, new technologies can take a drop of blood or saliva and read someone’s whole genome in about a day, for as little as $1,000 (down from close to $47,000 six years ago). Unsurprisingly, they don’t get everything right. No one knows for sure how far off the results are, and how much the accuracy varies from one test and company to another.
That’s one of the main challenges facing those who are at the forefront of a new wave of health care, called precision medicine, which depends on such whole-genome sequencing for everything from treating heart disease to developing patient-specific cancer treatments. The challenges of genetic testing accuracy have prompted the U.S. Food and Drug Administration (FDA) to get involved. It’s not out to bust companies for poor practices or false claims (at least, not yet) but rather to get them and other experts working together to improve the science, through a program called precisionFDA.
Dr. Taha Kass-Hout, FDA’s chief health informatics officer, compares the agency’s new collaborative approach to Wikipedia’s. “If you have a Wikipedia article, we’re all interested in updating it and making sure it’s always current and always great,” he says. “And that’s really what we’ve done with precisionFDA.”
PrecisionFDA provides a cloud-computing platform where companies and other researchers can test and refine the software that reads the raw results of gene-sequencing machines and assembles them into a transcript of someone’s genetic code. Wiki-style, participants can also share any of their data and experiences with others, in order to advance everyone’s understanding.
The program has gained about 1,000 participants internationally since it was introduced in December 2015. That includes individuals, institutions like the American Heart Association and Emory University, pharma companies like Roche, genetics-testing companies like Illumina and 23andMe, and Silicon Valley firms like Intel. Government bodies such as the National Institutes of Health (NIH) are also involved.
Why Decoding DNA Is So Hard
Close to 6.5 feet long, if stretched out, an entire genome can’t be analyzed in one piece. Instead, it’s chopped into little fragments. Reading technologies take advantage of the basic property of DNA: Each of the four possible chemical bases (letters of code) that join the double-stranded DNA molecule binds to only one of the other chemical bases (forming what look like steps on a ladder). Some reading methods, for example, add color-tagged bases to the DNA. By seeing where certain colors appear, analyzing machines can tell what bases in the DNA they have glommed onto. Sequencing machines will read hundreds or even thousands of copies of each fragment, to ensure that any erroneous readings don’t make it into the raw readout of every letter pair in each of the DNA fragments (a data file called FASTQ).
All of that is actually the easy part, thanks to the latest technologies.
