"Our hair follicle contains nucleic acid DNA, while our hair shaft contains mitochondrial DNA.
Hair roots are at the base of our hair, where the fibers exit the skin. The hair root still contains living cells with DNA that can be extracted and analyzed.
In conclusion, these studies totally debunk the myth that there is no nuclear DNA in hair shafts. Instead there is plenty of nuDNA present, but this DNA has become highly degraded during the formation of the hair shaft.
Hair analysis can be performed to determine if two people are related through blood. Hair structure and DNA from cells adhering to the root of the hair can be used in forensic hair analysis to assist identifying a culprit. Hair samples are examined under a microscope after being tested with particular substances.
Hair suitability for DNA examinations
A microscope is used to examine the root end of the hairs, in order to determine if they are suitable.
In order to identify a person, nuclear DNA is required. Traditional methods can get it out of hair with a root, though if it fell out more than a week ago it could be a problem, said Suzanna Ryan, a forensic consultant and lab director. “Hairs need to be in a growth stage in order to obtain nuclear DNA,” she said.
Unlike other criminal evidence that may be easy to remove such as personal possessions, fingerprints or footprints, hair strands are harder to detect and remove and thus very often remain at the scene of the crime.
DNA extraction
Briefly, a hair follicle or 3 pieces of hair shaft approximately 1 cm in length were added to a 3x3mm diameter tube. Next, 100 µL of Digestion Buffer was added to the tube and vortexed for 10 seconds. The tubes were then incubated at 85ºC for 10 minutes and given a quick spin in a centrifuge.
In some people, traces of cell nuclei may be found in the hair itself, not only in its root, but this is quite rare. In most cases, nuclear DNA is broken down into its building blocks, and if a hair lacks a root, it will be impossible to extract a useful DNA sample.
Because the hair specimens are collected at home, the results of hair follicle DNA tests cannot be used in court. At least six to ten strands of hair with the follicles intact are required for us to extract enough viable DNA for this test.
People usually ask what the accuracy is regarding the paternity test with hair. The success rate of this test is up to 80%. However, you should also keep in mind that the way samples are handled and kept safe plays an important role during the evaluation process.
Unfortunately, cut hair (which I am assuming is what you have) does not contain the necessary material for DNA testing. If he had any teeth pulled that she had saved, that would be a good source. Even sometimes a razor will work.
Individualizing hair specimens requires not just a DNA match, but a nuclear DNA match.
Nails contain genomic DNA that can be used for genetic analyses, which is important for large epidemiologic studies that have collected nail clippings at baseline and for future epidemiologic studies that consider collecting nails as a DNA source for genetic analyses.
You could fit 90,000 strands of DNA side by side in a single adult human hair. Yup, that's very much true. DNA strand is a very thin molecule averaging only about two nanometers in width. That is roughly two billionths of a meter.
DNA is present in adequate quantity in the crown body, root body, and root tip of the teeth. However, high quantity of DNA can be specifically obtained from root body.
Over the years, keratin has been extracted from chicken feathers, beaks, claws, nails, horns, hooves, human hair and toenails. The other significant source of keratin is wool.
Because hair can be grouped into three different racial groups it can be used to identify if it came from someone of European, Asian, or African ancestry. As such, hair can be used to exclude people of certain racial group as suspects or as having been at a crime scene.
DNA, or deoxyribonucleic acid, is the building block for the human body; virtually every cell contains DNA. The DNA in people's blood is the same as the DNA in their saliva, skin tissue, hair, and bone. Importantly, DNA does not change throughout a person's life.
The most common reference samples collected from known individuals are blood, oral/buccal swabs, and/or plucked hairs (e.g., head, pubic).
Can a toothbrush really be used for DNA testing? The answer is Yes. Our in-house geneticists have undertaken viability studies to prove that used toothbrushes can be a good source of DNA.
For paternity testing, saliva samples are usually used, as blood is more difficult to obtain and hair cannot always be clearly assigned. A swab of the oral mucosa is sufficient to obtain the sample. A paternity test requires at least two samples: one from the child and one from the possible father.
While not all these bodily substances provide ideal DNA samples, testable DNA can often be extracted from all of them. In every case, what is being tested is the DNA contained in cells of human tissue, whether found on their own or carried by another substance, like earwax, sweat or mucus.
If nails are to undergo DNA testing, cells are collected using any of a variety of methods, including swabbing the nails, scraping nails and collecting debris, or placing nails directly into a tissue digestion buffer. DNA isolation then occurs, typically via an organic or commercial kit-based extraction.
It is possible to obtain DNA from almost any human sample, including nails, blood, sperm, and objects that contain saliva, such as chewing gum.