How 23andMe Personal Genetic Service Works

Sample processing typically takes 4-6 weeks from the time your sample is received at the lab. However, these processing times are estimates, and are not a guarantee that your results will be returned by a particular date. While samples are processed in the order in which they are received, some samples may require additional steps to be processed successfully, which may extend the processing time.

You will receive an email when your results are available to view in your online 23andMe account.

The information available to you from the 23andMe Personal Genetic Service will be presented in the context of our web-based reports, tools, and features accessible through your account online.

Within your online 23andMe account, you will have the ability to print individual reports (available for select reports only) or a summary of all your results.

Keep in mind that 23andMe is predominantly an online service, and we do not provide a printed or printable report via mail or email. In order to receive the service, you need to have a valid email address from which you can send and receive messages. You will also need access to a computer or mobile device that connects to the internet.

Our genomes, which are composed of DNA sequences, contain the instructions for making every cell in our body. Most of our DNA sequences are identical from person to person, but there are specific positions in the sequence that are known to vary between individuals. For example, at the same position, one person might have the DNA letter C while another person might have a T. These DNA differences are called genetic variants. 23andMe analyzes your DNA by looking at certain genetic variants in the genome. We determine which version of the genetic variant you have at each position using a process called genotyping.

Although the human genome is estimated to contain about 10-30 million genetic variants, many of them are correlated due to their close physical proximity to each other. Thus, one genetic variant is often representative of many nearby variants, and the specific variants we look at provide very good coverage of common variation across the entire genome.

Want to learn more about genetics? Visit our Genetics 101 article.

23andMe analyzes your DNA by looking at certain genetic variants across the entire genome—chromosomes 1-22 (autosomal DNA), sex chromosomes (X Y), and mitochondrial DNA (mtDNA).

Once our lab receives your sample, DNA is extracted from cells contained in your saliva. The lab then copies the DNA many times—a process called amplification—duplicating 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 label on each probe identifies 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:

Though you may hear both terms in reference to DNA, genotyping and sequencing refer to slightly different techniques.

Genotyping is the process of determining which genetic variants an individual possesses. Genotyping can be performed through a variety of different methods, depending on the variants of interest and the resources available. For looking at many different variants at once, especially common variants, genotyping chips are an efficient and accurate method. They do, however, require prior identification of the variants of interest.

Sequencing is a method used to determine the exact sequence of a certain length of DNA. You can sequence a short piece, the whole genome, or parts of the genome (such as the “exome," which are the regions of the genome that contain the instructions for RNAs (ribonucleic acid) and proteins). Depending on the region, a given stretch of sequence may include some DNA that varies between individuals, in addition to regions that are constant. Thus, sequencing can be used to genotype someone for known variants, as well as identify variants that may be unique to that person.

23andMe uses genotyping, not sequencing, to analyze your DNA. Sequencing technology has not yet progressed to the point where it is feasible to sequence an entire person’s genome quickly and cheaply enough to keep costs down for consumers. It took the Human Genome Project, a consortium of multiple research labs, over 10 years to sequence the whole genomes of just a few individuals.

For people with specific needs (undiagnosed medical issues, for example, or intense curiosity and a generous budget), sequencing will become a more and more attractive option. For now, though, genotyping technologies, such as those used by 23andMe, provide an efficient and cost-effective way of evaluating genetic variation in individuals and across populations.

The 23andMe Personal Genetic Service can only be performed using a saliva sample collected with the saliva collection kit that we provide. The size of the saliva sample required for analysis is about 2 mL or around ½ teaspoon.

Saliva samples offer a convenient and non-invasive method for DNA sample collection compared to hair and blood samples. Cheek swab samples of DNA (as you may have seen on television programs or in movies) do not consistently provide enough DNA for the testing that we conduct.

Unfortunately, we are unable to analyze any other type of sample.

Most people who are able to produce saliva (~2 mL) and are able to spit can usually produce a viable sample.

Individuals who are unable to spit may not be able to provide a sample using our collection kit. Drool (found outside the mouth) does not contain sufficient amounts of DNA for analysis; only saliva (found inside the mouth) can be used.

If you have received a bone marrow transplant, we cannot recommend that you participate in 23andMe. If you are undergoing medical treatment that reduces your white blood cell count, such as chemotherapy, it is best to wait at least two weeks after your last treatment or until your white blood cell count has returned to normal.

Learn more about who can use the 23andMe kit.

No, one collection kit is needed per person.