I just received this very interesting and informative piece from Ancestry concerning my Ancestry DNA test, which is currently undergoing lab examinations in the US. I think it goes a step further to explaining how saliva samples are tested, and result obtained. Note the text is not my own; full credit and copyright is Ancestry’s:
“You’ve spit and put your saliva in the mail. Within a few days, your sample will make it to the lab. Once it arrives, it begins a journey that will take your saliva through many steps before you see the results online.
1. Your saliva sample has DNA in it, but that DNA isn’t ready to read yet. It’s stored inside immune and cheek cells. The first step at the lab is called extraction. Your sample is put into a plate in its own container with 95 other samples and then given to a series of robots that will take a small sample of your saliva and start processing it. Get comfortable with the other 95 samples – they will be with you for the rest of your journey! To extract the DNA, your saliva will be exposed to chemicals, spun at over 10,000 rpm, and all kinds of cell parts and pieces will be removed.
2. Next comes amplification. In this step, we make up to a thousand copies of your DNA. If you are thinking that is a lot, you’re right. This is done through a process called PCR (Polymerase Chain Reaction). Your sample is moved to a new robot that guides it through all kinds of chemicals, enzymes, and cycles of heating and cooling. Once we’re done, we have a lot more of your DNA than we started with. Now, we’re ready to read it.
3. How do we actually read your DNA? We start by applying your DNA to a SNP (pronounced “snip”) chip, or microarray. This SNP chip has been designed to read the 700,000 markers that will ultimately tell you your ethnicity estimate and which AncestryDNA members you are related to. The chip contains manufactured DNA that will bind to your DNA that we will then read. This technology is advancing and becoming better and better even as you read this.
4. Reading the SNP chip is a complicated stage of the process that uses a lot of science and math. Another robot communicates the final results from the chip. We need to be able to read at least 98% of the SNPs that we test; otherwise, we won’t be able to give you any results.
5. If we received enough data back, the As,Ts,Cs, and Gs that make up sections of your DNA are turned into a raw data file:
How do we determine your ethnicity estimate?
We take the data from your 700,000 markers that we just analyzed at the lab and compare it to population data from 26 different regions.
We run this comparison 40 times to get the best estimate of what regions your family genetically connects to based on current research. After running the comparison, we give you an ethnicity estimate. It is just that: an estimate. The estimate could change over time, depending on what new research might reveal. The example below shows what a set of ethnicity results could look like.
Your ethnicity results are unique to you. If you had additional family members tested, their results might look different. How is that possible? It comes down to the random nature of genetic inheritance. You received a random 50% of each of your parents’ DNA; because inheritance is random, a sibling typically won’t inherit exactly the same DNA as you unless he or she is an identical twin.
How do we determine matching?
Once your DNA is analyzed, we can compare it to everyone else in the database. We have more than 1 million samples in the database now, and we will continue to compare your genetic data to anyone else who takes the AncestryDNA test. Depending on how much DNA you share with any given person in the database we estimate a possible relationship. This is how DNA can help you find cousins you never knew you had.
You will be able to contact and see tree data for your matches if you have a subscription and your match has a public tree linked to their DNA results. This is one of the perks of having a membership and is a huge help in trying to identify where the common connection is between you and your matches, not to mention you will then have access to records where you can find out more about your ancestors and how they lived.
After you get your results look for updates and check out our blog to stay informed.”