5 Things You Need to Know About Hair DNA Tests

Learn about hair DNA testing, a DNA testing alternative, and discover 5 things you need to know about them, including how it works and when it’s used.

When you hear the term hair DNA test, the first thing that might come to mind is a true crime movie or TV show that you’ve watched. Hair is regularly gathered at crime scenes, just like in the movies, but did you know that it is now regarded as unreliable and is rarely used as forensic evidence? The FBI even admitted that testimony based on microscopic hair analysis was incorrect in at least 90% of instances. As a result, there is skepticism about hair DNA testing as a means of determining ancestry or DNA sequencing. Today’s researchers, on the other hand, aim to change that. 

There are several issues with utilizing any DNA as evidence, many of which stem from the possibility of contamination. This was the case in the murder investigation of Jane Mixer, a 23-year-old law student, who was murdered in March 1969, and her death remained unexplained for over four decades. Finally in 2005, retired nurse Gary Leiterman was charged with the crime by Michigan State Police.

Leiterman’s DNA was detected in drops of perspiration found on Mixer’s tights, but it wasn’t the only DNA discovered at the scene. DNA from John Ruelas, was discovered in a sample of blood obtained from a single drop located on the victim’s hand. It may have been difficult to figure out who murdered Mixer if it hadn’t been for the fact that Ruelas was only 4 years old at the time.

The presence of Ruelas’ DNA on Mixer’s hand indicated that the DNA samples had been contaminated in the lab, which may occur when protocols aren’t followed correctly. Despite the lab’s inability to explain the Ruelas mix-up, they claimed that the DNA findings from the sweat drops were accurate, and the jury believed them, leading to Leiterman being charged.

Aside from laboratory errors, DNA contamination at a crime scene is also a possibility. These aren’t the only issues that crime scene investigators face: DNA may deteriorate fast when exposed to moisture or direct sunshine, and there are occasions when there isn’t enough DNA to gather.

The use of ‘touch DNA,’ which has just lately been used as a solution, is one option. This is genetic material transmitted by a person’s short touch with a surface, such as a countertop or a door handle. The approach, however, is based on the examination of a small number of skin cells, which might be contaminated by secondary transfer. For example, if two individuals shake hands, one of them may contact a surface and leave the other’s DNA behind.

In summary, obtaining a clean and usable DNA sample adequate for precise identification may be challenging, and when mistakes do occur, the repercussions can be catastrophic - the greatest example being a false conviction.

Researchers recognize that additional work is needed before the approach may be utilized in forensic laboratories and, eventually, in courtrooms. Researchers will need to evaluate a wider sample of people, with people of various ethnic origins. Furthermore, the approach presently only requires a thimbleful of hair, which is unlikely to be accessible in real-world situations. For the procedure to be useful, it must be feasible to analyze a smaller sample - ideally a single strand. Researchers must also put the protein markers they choose through thorough testing to verify that they are trustworthy.

With all that being said, here are five things you need to know about hair DNA tests:

1. How Effective Is It?

Hair transplants with undamaged roots have a success rate of 60% or less. It’s critical that 7-10 hairs are present, and that they aren’t shed or clipped. Although there are more effective procedures, hair is one of the most accessible and inexpensive ways to collect DNA.

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 analysis can also be done to screen for metal toxicity, such as lead or mercury poisoning. However, hair analysis is rarely utilized for this sort of testing.

Unless the sample’s validity can be officially validated through the correct chain of protocols, the hair samples and their findings are not generally applicable to legal DNA testing.

3. How Does It Work?

Hair is a protein that develops from the skin’s hair follicles. A hair develops in the hair follicle for several months before stopping and falling out. In the follicle, a new hair develops. Because hair grows slowly, it takes weeks for a hair sample to indicate changes in the body. Recent changes in the body, such as drug usage in the last several days, are not visible in hair samples. A hair analysis, on the other hand, may reveal drug usage or chemical exposure during the previous several months.

4. What Are Some Other Real Life Applications of Hair DNA Testing?

Humans shed an average of approximately 100 head hairs per day, and because hair can be easily transferred during physical contact it is commonly submitted as forensic evidence to help establish associations between people (e.g. a victim and suspect) and/or people and a crime scene.

Such associative evidence is especially useful in violent crimes where physical contact is likely to have occurred such as sexual assault, homicide, and aggravated assault. Crimes less likely to have involved physical contact such as armed robbery would typically involve collecting clothing or other items that may have picked up hair that could be used to identify suspects.

In 2009, the National Academy of Sciences released a report called “Strengthening Forensic Science in the United States: A Path Forward,” which stated that since the advancement of DNA analysis, microscopic hair analysis should be confined to establishing which hairs to test, and whether hairs share similar characteristics, but should not be considered a reliable tool for the identification of individuals suspects.

5. What Sort of Problems Can Occur When Testing Hair for DNA?

  • The hair follicle is the component you really want for DNA testing, and it’s also the part that’s least likely to be present in a preserved strand of hair.
  • The sample’s age is the age of the sample. Obviously, if samples from a woolly mammoth — which are a little older than any sample from anyone’s great-great grandmother — can be tested successfully, these hair strands can be examined as well. However, keep in mind that teams of scientists worked on those old samples, and you’re probably not in a position to pay for the sorts of forensic testing that may be necessary.
  • The third issue is that locating a lab to do the test for you is more difficult than purchasing a kit from a popular company. Hair testing is not available from any of the regular genealogical DNA test businesses at this time, and it is unlikely to become available in the near future.

As more and more people become interested in learning more about their DNA, whether it be for genetic reasons, ancestor information and much more. There are more readily available and accurate tests that can be taken than hair DNA tests, which yes are effective, but not the most accurate.

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