Yielding virtually the same amount of DNA per volume and the same DNA quality, saliva can be considered as good and as reliable a source of DNA for a wide variety of genetic applications. One thing to note however is that not all oral samples are equal.
The saliva collection kit includes a buffer solution that is added to your saliva immediately after you finish providing your sample. This solution stabilizes the DNA and prevents bacterial contamination. Buffered samples are stable at a wide range of temperatures (-4ºF to 122ºF or -20ºC to 50ºC) for up to 6 months.
Answer: The DNA in our blood is the same as the DNA in our saliva. For convenience, the JScreen test is usually done on saliva, and is just as accurate as testing on DNA from blood.
Common reasons a sample may fail
This can happen if the cap is installed incorrectly or not screwed on tightly enough. The blue stabilizing solution did not mix well enough with the saliva sample. Contamination (something other than human saliva and stabilizing liquid in the collection tube), including: bacteria.
It's not at all unusual for a little excess saliva to get mixed in with cheek cells when collecting DNA for a paternity test. As a result, the sample and even the mailing envelopes may become a little wet. If mailed while damp, packaging could tear and swabs can become contaminated.
Processing food by cooking leads to the partial or complete breakdown of the DNA molecules, whatever their origin. Likewise, most DNA that is eaten is broken down by our digestive systems but small quantities of fragmented DNA can pass into the bloodstream and organs without having any known effect.
DNA from saliva generates highly concordant data compared with DNA from blood for the same donor, as demonstrated by the genotyping concordance and CNV reproducibility.
If the swab or the container is contaminated, the test may be wrong. If the person obtaining the same did not follow the correct procedures, it could impact the test's outcome.
A saliva swab will offer a rate of success of 95% which means that there will very unlikely be any problems concluding laboratory DNA analysis. Hair paternity Testing is less accurate because the actual hairs we shed naturally after we shower, brush our hair or the ones that we cut or shave do not actually contain DNA.
As a general rule, don't put anything in or near your mouth for 30 minutes before spitting in the tube. For example, if you kiss someone before collecting your saliva, you're actually swapping a little bit of DNA with your partner and that can invalidate your sample.
Brush your teeth and/or use mouthwash. Don't eat, drink, smoke, or chew gum or tobacco for 30 minutes after brushing your teeth and before providing your saliva sample. Gently rub your cheeks from the outside (pressing them against your teeth and gums) before spitting into the tube.
DNA is extracted from your cheek cells, which are collected when you rub the swab against the inside of your cheek. Eating, drinking, or brushing your teeth will not change your DNA, but it can make for a messy sample.
According to DNA paternity testing accreditation guidelines, a paternity report must show a CPI of greater than 100 (and a probability of paternity greater than 99.0%). Most courts, child support agencies, or other legal entities require an accredited report (see Legal Paternity Testing for more information).
An autosomal DNA test is the best investment for most beginners; it can identify relatives between five and seven generations back, across both maternal and paternal lines. Only men can effectively use a Y-DNA test, which identifies male relatives on the paternal line reaching back 60,000 years.
Before you swab, make sure you haven't eaten or drank anything - the optimal time to take the test is first thing in the morning before you've brushed your teeth and had that first cup of tea of the day.
High probabilities of 99% and above are commonly seen in DNA paternity testing, but never 100%. This is because results are based on statistical calculations. A result of 100% would only be possible if AlphaBiolabs tested every male of the same ethnicity as the biological father.
If you are not considered the biological father, the report shows “0.” The Combined Paternity Index is an odds ratio indicating how many times more likely it is that the possible father is the biological father than a randomly-selected unrelated man with a similar racial background.
Double-strand DNA breaks (DSB), although rare, are perhaps the most lethal mechanism and are often produced by ionizing radiation (Pastink et al., 2001; Siever et al., 2003).
DNA can be damaged via environmental factors as well. Environmental agents such as UV light, ionizing radiation, and genotoxic chemicals. Replication forks can be stalled due to damaged DNA and double strand breaks are also a form of DNA damage.
In addition to the intrinsically generated lesions to DNA, dietary mutagenic chemicals, ultraviolet and ionizing radiation, and heavy metals are environmental agents that damage the genome, causing DNA cross-links, adducts, and oxidative cleavage (18).
To improve the amount of DNA collected, take two or more samples from different sides of the mouth, or take them several hours apart. Do not eat, drink anything other than water, smoke, chew a gum, brush your teeth, or use mouthwash for at least one hour before taking the test.
Rinse mouth thoroughly with water to remove any food particles or other contaminants, then wait a full ten minutes before collecting the saliva sample. Collecting saliva too soon after rinsing may reduce the amount of DNA that can be extracted, and it can also affect hormone/biomarker analyses.
Do not eat, drink, smoke, chew gum, brush your teeth, or use mouthwash for at least 30 minutes prior to providing your sample. Collect the recommended volume of saliva.
Avoid putting anything in your mouth for at least an hour prior to collecting cheek-cell samples. Foreign particles from food, liquids, toothpaste and tobacco byproducts don't alter the DNA but they can mask it. The consequence is that the sample becomes degraded and therefore unusable for paternity testing.