What Happens After I Spit? A Saliva Sample’s Saga
March 3, 2009
home that allows technicians to process batches of 96 samples. Technicians remove a portion of the saliva from each tube, then put the rest of the sample aside so they can try again in case their first attempt fails. If a second attempt to extract DNA from a particular sample fails as well, we send a second kit to the customer who provided it (free of charge) so that person can provide a fresh (and hopefully DNA-rich) one.A sample may lack enough DNA for extraction if the preservative solution is not released when the customer snaps the cap onto the funnel during the collection process. A sample could also contain an insufficient amount of DNA simply because there are not enough cells floating around in it. Some people seem to have less DNA in their spit, though almost everyone has enough for the purposes of our analysis.Step Three: GenotypingSamples that yield sufficient quantities of DNA are submitted for genotyping, which scans the genetic material at the approximately 580,000 markers (SNPs) included in our service. This process is also performed in batches of 96 samples. And once again, we monitor the process to make sure it is going as expected. If it isn’t, we try again. In this case a sample is re-run if the analysis process cannot determine its genotype at a minimum of 98.5% of the locations we probe (roughly 570,000 out of the 580,000). If the second attempt fails as well … we ship the customer another sample collection kit for free.Once a sample has been successfully analyzed, the laboratory sends the resulting data to 23andMe along with the barcode that came with the sample. That allows our database to deposit the information in the proper account and send an automated email notification to the customer who holds it.With all the things that can go wrong, the sample analysis process may seem a little precarious. But it’s actually quite robust — the vast majority of samples sail right through without a hitch. If things do go smoothly, we can generally return data within eight to 10 weeks of the date a sample is sent to the lab.My name is Varsha Baichwal and I work here at 23andMe as Director of Operations. You can share your genome with me if you wish – my 23andMe ID is “varsha”.