Suggestions on How to Optimize Spit Kit Collection Efforts

Here’s a good start on ways to improve your odds of getting better results from a spit kit. They have a separate blog on their blog that has some additional tips – I added it below. For both blog posts, follow the instructions that came with your spit kit since some of the suggestions on their blog posts are directed at lab personnel processing DNA kits and won’t apply to individuals providing the spit.

It  misses a couple of key items:

Get as close to the line in your spit kit as you can without going too much over or under. Bubbles don’t count since they will usually pop on their own.

Collect the DNA within 30 minutes as spit DNA tends to start degrading in about 30 minutes. Although they do cover this in a separate blog post:

Some people don’t produce enough DNA in their spit for a successful result. For those individuals, a spit kit will likely never succeed. In those cases, a cheek swab may be a better option.

For those with dentures, best to remove them before collecting the sample and not use any denture adhesive for 12 – 24 hours before the collection attempt.

If you have, or are undergoing, anything that affects your blood or DNA (blood transfusion, bone marrow transplant, certain types of grafts, chemotherapy, radiation therapy), it can affect your ability to collect a DNA sample. Contrary to where Ancestry says chemotherapy won’t affect the DNA result, it can and Ancestry’s DNA kit uses spit DNA which relies on white blood cell count for DNA extraction. Cheek swab DNA extraction relies on the skin cells of your cheek, but can also be affected in some cases.  A better answer was given by 23andMe in its FAQs section: Also, FamilyTree DNA (FTDNA) has two topics on the subject (see links below).

Our sample collection method is not designed for:

    • Individuals who are unable to spit; these individuals 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.
    • Individuals who are undergoing a medical treatment that reduces your white blood cell count, such as chemotherapy; these individuals are advised to wait at least two weeks after the last treatment or until the white blood cell count has returned to normal.
    • Individuals who have received a bone marrow transplant. In the event that the analysis was successful, it still would be unclear whether the results were based on DNA from you or from your donor.

FTDNA links: and

I have been sick. Will this affect the sample?

Most illnesses will not affect your DNA and therefore will not affect your ability to test. However, if you have or have recently had an illness that has required antibiotics such as strep throat (Group A Streptococcus), you should wait until you are fully recovered before testing. Doing so will ensure that your samples contain your DNA and not that of the bacteria that caused the illness.

Medical situations that would be of concern would be: known genetic disorders, bone marrow transplants, and/or facial reconstruction with donor skin grafts in the mouth. In any of these cases, please contact us and discuss the specifics of your situation to determine if we can get a usable sample.

– – – –

I’ve had a blood transfusion, radiation therapy, or surgery recently. Will this affect the sample?

We recommend waiting one week after having serious surgery or radiation therapy before taking a sample. We suggest waiting 1-2 weeks after a blood transfusion as well. However, even if you take the sample right away, the medical treatment you have had should not affect the sample, and we will be able to get a good result.

Medical situations that would be of concern would be: known genetic disorders, bone marrow transplants, and/or facial reconstruction with donor skin grafts in the mouth. In any of these cases, please contact us and discuss the specifics of your situation to determine if we can get a usable sample.

Less rare is the Chimera effect, but it’s often raised by non-experts in trying to explain why you and somebody don’t show as genealogical matches. Here’s the Wikipedia article on Chimera in genetics: You can thank shows like CSI for making the Chimera situation a big deal when it’s fairly uncommon. Also, if Chimera is in play, you should still show as a match to a close relative; the degree of relationship may be off a bit (for example, a parent showing up as a grandparent).

Identical twins don’t share exactly the same DNA. It’s pretty close and for the standard autosomal or genealogical DNA testing done, it probably would show as being exactly the same because the tests aren’t testing 100% of your DNA. For tests like AncestryDNA, FTDNA, 23andMe, etc., they are usually only looking at 500,000 – 800,000 SNPs out of over 3 billion SNPs in your DNA.

There may be other things that improve or worsen your odds of getting a successful DNA result from a DNA test, but the above are some of the most common questions and known problem areas.



About Wichita Genealogist

Originally from Gulfport, Mississippi. Live in Wichita, Kansas now. I suffer Bipolar I, ultra-ultra rapid cycling, mixed episodes. Blog on a variety of topics - genealogy, DNA, mental health, among others. Let's
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1 Response to Suggestions on How to Optimize Spit Kit Collection Efforts

  1. Pingback: DNA Testing Uses Up a Portion of Each DNA Sample Submitted – November 29, 2019 | Ups and Downs of Family History V2.0

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