Once our lab receives your sample, DNA is extracted from cells preserved in your saliva. The lab then copies the DNA many times - a process called amplification - growing the tiny amount extracted from your saliva until there is enough to be genotyped.
In order to be genotyped, the amplified DNA is "cut" into smaller pieces, which are then applied to our DNA chip (also known as a microarray), a small glass slide with millions of microscopic "beads" on its surface. Each bead is attached to a "probe," a bit of DNA that matches one of the genetic variants that we test. The cut pieces of your DNA stick to the matching DNA probes. A fluorescent signal on each probe provides information that can tell us which version of that genetic variant your DNA corresponds to.
The following video gives you a behind-the-scenes look at some of these steps taking place at our lab:
Although the human genome is estimated to contain about 10-30 million genetic variants, many of them are correlated due to their proximity to each other. Thus, one genetic variant is often representative of many nearby variants, and the variants on our genotyping chip provide very good coverage of common variation across the entire genome.
Our research team has hand-picked tens of thousands of genetic variants linked to various conditions and traits in the scientific literature to analyze on our genotyping chip. As a result we can provide you with personal genetic information available only through 23andMe.