DNA Samples from Blood, Hair, Fingernails, and Other Specimens

Often, a parent wants to secretly find out whether or not a particular man is the father of a child, without the other parent or the child knowing that they are doing the test. For example, many mothers are not sure whether or not their husband or secret boyfriend or a past acquaintance is really the father. Asking the husband to swab the inside of their cheek may be too suspicious, of course.

For these cases, the parent can try to collect another DNA specimen. There are 3 factors to consider:

1. What kind of sample would be least difficult to collect?
2. What kind of samples would be better as regards success in testing -- what kinds of samples can provide enough DNA?
3. What is the extra cost of testing different kinds of samples?

Below are some examples of alternative and discreet DNA specimens you can consider trying to collect. We've had a very high success rate with these over the past several years, using current technology.

• Sperm / semen: Grade A. This is usually collected from a used condom. Do not bring in the entire condom, unless it is just hours old. It is best to either swab the inside of the condom or collect it on tissue and let it dry, within hours after it was used. Wet semen will degrade quickly, as bacteria reproduce and destroy the cells with DNA. Put it inside a paper envelope (not plastic) and let it dry there.

• Blood: Grade A or B or lower. Fresh blood which is dried while fresh and brought to us before it gets too old is a good specimen for DNA extraction. For example, bandages from injuries have worked very well. However, please keep in mind that red blood cells have no nucleus so no DNA. The DNA is actually obtained from the very small quantity of white blood cells (antibodies) in the blood. The blood can be dried on a bandage or gauze, napkin, swab, or clothing, for example. However, please be aware that blood degrades quickly. Liquid blood which is not fresh may not be as good as older dried blood.

• Fingernail or toenail clippings: Grade A or B. We've had a success rate of over 90% the past several years on the latest equipment. Just try to get more than one fingernail if you can. Several fingernails is best. Please understand that fingernails and toenails are made of keratin (like hair), not cells with a nucleus containing DNA, so it's not easy, but they are produced from cells and some cells are embedded or attached. The more fingernails or toenails you have, the better. For example, we have gotten profiles from 1 toenail, and from a few tiny baby fingernails, but the more you have, the more likely and more quickly we can get a result. Fingernails and toenails have been collected from trash cans or from offering to cut nails. Just put the fingernails or toenails into a paper envelope and seal it (or a plastic bag is okay if they are already dry and you want to protect them against moisture such as putting them in your pocket).

  Notably, while DNA is not well concentrated in fingernails and toenails, it does tend to be more stable over time compared to some other kinds of stored specimens. Fingernails stored at room temperature for 10 years and longer have yielded enough DNA. Fingernails have also been recovered from exhumed corpses at an advanced stage of decomposition and analyzed successfully. There is usually enough stray DNA embedded in the nails (from the process in which mammals create the material from cells) for DNA extraction and typing. We have processed fingernails from the deceased and gotten a good result at normal costs.

• Chewing gum: Grade B to C. Sugarless chewing gum is better. Wrap it in tissue and put it into a sealed paper envelope.

• Hair: Grade B to C (depends on sample). If the hairs have roots, then it usually works. However, cut hair is generally not accepted, as the concentration of DNA in cut hair is usually too low (unlike fingernails) for a paternity test. Obviously, pulling somebody's hair out to get the roots is not discreet. Some people have come in with hair with roots found in hair brushes, shed hair from a pillow, and hair from a shower drain. (One customer's tactic was to clean the shower drain and entire shower area completely before the person took a shower, put a screen inside the drain, ask them to wash their hair, and then see what they can collect from the screen and floor of the shower. Obviously, if there is hair from more than one person collected, then it won't work.) The hairs must have roots. You can usually see roots with or without a magnifying glass. In our office, we have a magnifying glass and also two microscopes. Just put the hairs into a paper envelope (or a plastic bag is ok if they are dry). Shed hair tends to have significantly smaller root material than pulled hair. Strong brushes sometimes remove enough hairs with roots. Broken hair without roots must be discarded. Collections shed hair may require a significant amount of labor to sort through.

• Toothbrush: Grade C. Put it into a sealed paper envelope. We've yet to have a toothbrush fail, but success can depend on how much toothpaste they use (being similar to soap) and how well they rinse their toothbrush.

• Napkin wipe of the mouth: Grade B or less. If a person wipes their mouth onto a napkin, and if the napkin goes inside the mouth, then the napkin will typically collect epithelial cells like a mouth swab. So that we can best determine what part of the napkin entered the mouth, try to not change the shape of the napkin. We have identified the part of the napkin which entered the mouth from the shape of the used napkin, and/or stains, cut out that part with cleaned scissors, and gotten a DNA profile. For a child, it's easier if the parent can wipe the mouth.

• Cigarette butts: Grade C. More than one is preferred, but one butt has been enough.

• Water bottle, plastic spoon or fork: Grade C or D. Swab it thoroughly and send us the swab, or else bring the whole thing into our office, or mail it to us.

• Razor, nose blow tissue with mucus: Grade C or D. Send the whole item to us as-is.

• Tampon / feminine pad: Grade C. Dry it out as much as you can and as soon as possible, and get it to us as soon as you can. The main enemy here is bacteria and fungus which destroy DNA.

• Drinking straw, water bottle: Grade C or D. Unfortunately, a drinking straw can be easily wiped clean accidentally, so there is a storage and transport issue. A water bottle with its top on has been easier to deal with. If there is still liquid in the bottle, then cut a hole in the bottom and drain it first. Let it dry out.

Other kinds of samples are possible, but please talk with us first.

We call these "unusual samples" but they can also be called "forensic" samples.

The time to process unusual and forensic samples typically takes longer, from a few days to a couple of weeks or so more, depending upon the sample.

The extra cost depends on the kind and quality of the sample. Not all unusual samples have the same price. The cost is typically 4000 to 9000 baht extra per unusual sample. For example, if the cost for processing an unusual sample is 5000 baht, then added to the 11,800 baht cost of the paternity test, the total would be 11,800 + 5000 = 16,800 baht. However, we do not charge you the 11,800 baht for the paternity test if the sample isn't good enough. We do charge the cost of trying to test the sample, whether or not it works, so you must pay at least the 4000 to 9000 baht per unusual sample. Normally, people pay for the entire test, but if the sample does not work, then we either refund the 11,800 baht or else the customer provides an additional sample later. We do not refund the cost of testing the unusual sample, whether or not it works, as the laboratory worked on it.

Regarding quality of sample, the best samples are unfortunately not discreet. Swabs of the inside of the mouth are the best samples, because cheek (buccal) cells come off easily, have a nucleus with DNA, and last long enough when dried. They are the cheapest to process. For a baby or child too young to know what the swabs are for, this is much preferred. The challenge is for an adult or an older child who may suspect what is happening. Buccal swab samples normally collect a very large amount of DNA.

Many kinds of forensic samples typically have a small quantity of DNA and should be handled very carefully, because a little bit of contamination by another person's DNA can potentially cause significant contamination and a double profile (two peoples' profiles together). It's rare but it can happen. Of course, don't touch the part of the object which would have the DNA and which could can be cut off and tested. For example, if picking up a cigarette butt, pick it up by the end which burned, not the end which went into the mouth. Don't put them into your pocket on a hot day and sweat onto them. Try not to cough or sneeze near them, and don't talk when your mouth is close to them. Don't breathe onto them. Put them into a paper envelope and seal the envelope as soon as you can.

A paper envelope is much better than putting them into plastic, because they can dry out in a paper envelope. Bacteria and fungi are our enemies, in addition to DNA contamination by other people. Get the specimens to us as soon as you can. Please keep in mind that dead cells and the DNA inside degrade quickly (due largely to the enzymes inside dead cells). If samples get too old, or are not stored well, then it may not be cost efficient to extract DNA using routine laboratory testing within a reasonable budget.

Please be aware that old specimens may not work. For example, when a person dies, decomposition starts quickly as the enzymes of the dead cells start destroying the cell contents, somewhat like self-digestion (autolysis), destroying the DNA in the nucleus. For example, when police come upon a rotting body, they might not get a DNA profile by just scooping up rotting flesh to test, even though that rotting flesh was full of cells with nuclei originally. Similar issues apply to human tissues which are not preserved in some way. Forensic experts typically try to get teeth, hair roots, and fingernails, or analyze bones. (Teeth can be used either to compare shapes to dental records, or to extract material from inside the teeth for the DNA, as the insides of teeth are one of the best protected and most stable sources of old DNA.)

Mouth swab specimens which are dried usually have enough detectable DNA for months at room temperature. Some other kinds of dried samples also last a long time. Fingernail samples last a long time. However, many other kinds of samples degrade quickly.

Human tissues preserved in formalin / formaldehyde present a problem in that the chemicals damage the DNA and interfere with the process in the laboratory which tries to replicate / amplify the DNA.

We have obtained a DNA profile from tissue removed during surgery, but it is best to get the tissue to us reasonably quickly, not months later and poorly stored.

It is best to (1) dry specimens which have any moisture, and (2) store specimens in a cool place, for example in a refrigerator at temperatures around 4C or 40F, but without condensation, e.g., in clean paper storage.

It is possible to get DNA from long dead people, but the cost can run into the thousands to millions of dollars. For example, DNA has been recovered from ancient animals, such as from the inside of a well preserved tooth of Neanderthals. It was very expensive, delicate, and time consuming. Of course, many times attempts have failed for ancient animals. That's beyond the scope of this website.

Here we are talking about the costs to extract DNA commercially for consumers, and using standard equipment and chemicals for routine tests at reasonable costs to individuals. If you have a very high value case but an exceptionally poor source of DNA, then you can still talk with us, preferably as soon as possible.

We can also handle exceptional, special investigation cases, too.

Please feel free to ask any questions or discuss anything.

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