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Home DNA Testing

News and insights in the world of DNA and genetics for paternity, immigration and forensics

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On December 7, 1941 the Japanese struck Pearl Harbor in a surprise attack that decimated the US Pacific Fleet. Of the ships that were attacked few sank as fast or as completely as the Oklahoma, which listed and capsized within minutes after a rapid series of direct torpedo strikes.

Survivors from the Oklahoma described a surreal scene below deck of sloshing water and fuel oil, men trying to climb from the darkness through hatches, beating their way out with tools. Hundreds remained trapped in interior compartments. Of the dead on the Oklahoma, 36 were easily recovered and identified. The remainder were not able to be identified and were interred in communal caskets.

Approximately 74,000 soldiers from World War II still remain unaccounted for. About one-quarter of those are considered recoverable by the military’s Joint POW/MIA Accounting Command, the Hawaii organization that has relied on scientific and geopolitical changes to identify more than 600 long-lost MIAs since 2003.

The Joint POW/MIA Accounting Command’s military and civilian teams have tracked down aircraft wrecks and burial sites in remote locations, exhumed remains, and analyzed bone fragments and bits of material at the world’s largest forensic anthropology lab. They work with casualty offices from each branch to find survivors and collect DNA samples for matching. For each name, the military tries to locate at least two relatives who share a long-lasting form of DNA passed along maternal lines.

In Hawaii, Greg Berg, the forensic anthropologist who manages the joint command’s Central Identification Laboratory, cautions that the work to identify remains could take years, the process he warns is complicated by commingling of remains which is far more extensive than expected. Only five people have been definitively identified since 2003.

Still, “the commingling problems are not insurmountable, and [we are] confident in our abilities to eventually bring about case resolution,’’ Berg said by e-mail.

For more see: Boston Globe

By now you have heard the news: On October 3rd, 2011, Amanda Knox and former boyfriend, Raffaele Sollecito, won their appeal in an Italian court and were acquitted and freed for the murder of British student, Meredith Kercher. Despite a previous trial and guilty verdict based on supposed DNA evidence, both convicted parties won an appeal and a deeper trial over the evidence occurred.

While we could pick over all of the details of the case, we’ll leave that for another organization to discuss. Instead, allow us to focus alone on genetic evidence.

With no obvious motive, no independent witnesses and no confessions, the Italian prosecutors had to rely on genetic evidence found at the crime scene to convict Knox and Sollecito. This makes sense as genetic evidence is supposed to be iron clad.  Or is it?

The original conviction relied on traces of Sollecito’s DNA being found on the victim’s (Kercher) brassiere clasp, together with traces of DNA from both defendants being found on the knife allegedly used to slash Kercher’s throat. However, similar to our famous U.S. tales of botched crime scene evidence (ie. the Jon Benet Ramsey or OJ Simpson cases), the prosecutions evidence has been marred with rumors of bad police work and possible fabricated evidence. Furthermore, not only did the defendants know Meredith Kercher, but Amanda Knox lived with her.This complicates matters on an enormous level.

The first issue is called “contamination”. Unlike crimes where the victim and perpetrator don’t know each other, and therefore a genetic link is most likely an obvious connection, it is hard to do the same with roommates and their visiting friends – there will always be matching DNA present. And although DNA evidence puts a person ‘at the scene of the crime’; it does not necessarily prove they committed the crime.

Secondly, although DNA evidence can match the scene of a crime, it does not allow for “time-based evidence”. There is no telling if a match occurs because a victim or perpetrator was present at the time of the incident or exists because they were present at some other point in history.

Finally, although many people have been successfully prosecuted on DNA evidence, it is not failsafe or full proof. Typically, a DNA sample found on a murder weapon will be said to match the DNA of the suspect to the extent that only one person in one million would have the same profile. However, if a particular genetic profile is held by one person in, say, one million this means that in a country with a population of 60m will have 60 people that give a perfect mach for the DNA evidence and even more would match a partial profile of that evidence.

In the U.S., a man called Kerry Robinson was convicted a few years ago of gang rape. In an independent investigation last year DNA evidence from the crime scene plus Robinson’s DNA profile was shown to 17 ‘blind’ analysts with no contextual information: the 17 experts were hugely divided – 12 said the suspect could be excluded.

Although no one can or should doubt the genetic evidence is a powerful tool for solving crime, it is not perfect and it has it’s weakness, from false positives to human error.  One thing is for certain – this legal matter and it’s evidence will be scrutinized for a long time to come. Let’s hope that we can learn from it.

 

 

Read more: http://www.dailymail.co.uk/debate/article-2044935/As-Amanda-Knox-walks-free-DNA-evidence-trial.html#ixzz1ZlPcRlgY

 

New York State officials are hoping that genetic testing can help solve the mystery of a mountain lion which mysteriously appeared in Greenwich. DNA testing will be used to determine where the deceased young male mountain lion came from and, hopefully, how he got to Greenwich, NY in the first place. Along with how is the question of any criminal aspect to his appearance.  A mountain lion was killed by a driver on Route 15 in Milford, NY early Saturday morning. Officials believe that this same lion that had been spotted in the upper King Street area of Greenwich earlier.

The mountain lion was neither neutered nor declawed, according to DEP (Department of Environmental Protection) officials. But they do believe the lion was let go from captivity or released into the area.  Mountain lions are not native to this region of the state

Officials believe that by conducting genetic testing, examining the animal’s stomach content and checking to see if it was microchiped, they can determine where the mountain lion came from, including whether the animal is native to North America or South America.

After the crash that killed the mountain lion in Milford, there were three other reports of possible mountain lions, but DEP is not considering them to be credible because of a lack of photos or significant paw prints.

New York state DEP (Department of Environmental Protection) received an anonymous call on Sunday to report a large cat in the area of exit 31 on the Merritt Parkway in Greenwich. Later a call from a Greenwich family reported a large tan cat in the backyard of their John Street home, near the Audubon. The family described the cat as a mountain lion.

DEP Officials are testing “scat” or feces to determine what the second reported animal is.

DEP officials say that part of the investigation into the deceased mountain lion will be done in New York, where officials are checking on “permitted lions” to see if that generates leads. The closest mountain lion population is located in Florida. While the mountain lions roam, DEP officials do not think it is likely that a Florida mountain lion would have made the trip that far north.

DEP officials said mountain lions are most active at dawn and dusk and anyone with information should call 860-424-3333

 

 

When President Obama announced Sunday evening, May 1st,  that Osama Bin Laden had been killed in a United States military operation, many wanted physical proof that the person killed and taken into custody was in fact Mr. Osama Bin Laden.

At this time reports are confirming 3 ways the remains were identified: 1) Facial recognition software was used to match the remains with facial photos of Osama Bin Laden. 2) There was apparently a personal identification of the body by someone inside the complex (exactly who identified the remains is unclear).  3) DNA testing of the remains took place within hours of death.

DNA Testing is now fast and accurate. It no longer takes weeks but can be done in the matter of hours and has a 99.9% or better accuracy rate.  At least one question remains – who, how or what did they test to confirm that it was Osama Bin Laden?  Did they test a family member against his DNA? There is speculation that they could they have tested the purported Osama Bin Laden sample against DNA from his sister, which (according to reports) had been held at Massachusetts General Hospital after her death in Boston last year. Or did they somehow already have Osama Bin Laden’s DNA on file and test against that?

According to Dr. M. Al Salih, who works at DNA Reference Laboratory in San Antonio, TX, he is sure that the results are accurate.  “You can come up with a very solid and absolute certainty that that is him and nobody else. If you identify that individual through those markers, and you can compare and you can say, ‘They match,’ or ‘They don’t match.’” Salih went on to state that the technology is very precise and results are 99.9 percent accurate.

However, on the other side is Dr. Greg Hampikian, a biology professor at Boise State University, says if they can get DNA from one of his kids and their mother then they do a reverse paternity test to confirm his identity and he suspects that is the type of DNA testing that was done. However even with a 99.9 percent identification Hampikian says that this case is not closed. As a scientist, Hampikian says 99.9 percent does not equal a positive identification.

As is the case with most major events such as this, skeptics speculate that we have not received enough proof and conspiracy abounds. One thing is for certain, we love conspiracies and we will never really know the truth.

That’s right April 25th is National DNA Day.  It was proclaimed by both the US Senate and the House of Representative in 2003 and while you might not have the day off you might want to stop and think about just what DNA has done for us.

DNA Day is a remembrance of the day in 1953 when a gound breaking article on the structure of DNA was published as well as the the day that the Human Genome Project was completed in 2003.

DNA has made big changes in our lives whether we know it or not.  So this April take some time to think about DNA and some of it’s many uses:

1. In archeology DNA helps record genetic information of life on earth many centuries ago. This creates a data base that can be used to learn more about our planets past.

2. Genetic testing is used to determine the paternity or maternity of a child.

3. DNA testing can be used to help create a family tree or genealogical chart. Through genetic data bases one can trace lost relatives or find ancestors. Using both the Y chromosome and Mitochondrial DNA people can use DNA testing to establish ancestral lines (both remain unchanged for generations).

4. Prenatal genetic tests can help doctors determine whether or not the unborn fetus will have certain health problems.

5. DNA tests are also used to help solve murders and other crimes. In recent years many unsolved mysteries have been solved due to new ways of analysis as well as clearing many people found guilty of crimes that the did not commit.

6. DNA testing finds great use in the health field as DNA sometimes is the cause of rare medical conditions or heritable diseases.

7. Genetic testing is used in healths checks. For example it can be used to help determine the presence of viruses or cells that have mutated (causing cancer).

8. DNA tests are often used to reunite lost siblings or families or identify remains of the unknown. The genetics of a person leaves an indelible mark and this is used by police, military and authorities as well as individuals to confirm relationships.

9. DNA tests on new species or on material from outer space help scientists and researchers determine the origins of a species and where they stand with reference to known living forms.

In 2009 a new laboratory was opened at the University of Otago it was expected to unlock secrets about the genetic heritage of Pacific people, animals and plants according to scientists and anthropologists.

The ancient DNA laboratory, allows scientists to extract DNA from bones, teeth and plant matter. The DNA will be analyzed using the latest technology, including the university’s $1 million gene sequencing machine which was purchased in 2008. The facility is a joint project between 3 departments.

Ancient DNA did not necessarily mean from antiquity, according to Professor Matisoo-Smith. In scientific terms, ancient means any DNA samples which were not taken from living subjects. Matisoo-Smith did go on to say that some of the samples the laboratory would handle would be thousands of years old.

Already, projects were planned with samples from many parts of New Zealand, several Pacific islands and from Chile.

Representatives of Maori iwi whose ancestors’ DNA will be analysed in the laboratory spoke of their initial reluctance to allow their ancestors’ remains to be analysed because of the intrusiveness of the process.  They did however agree to allow the DNA analysis after discussions with Prof Matisoo-Smith and her staff which allayed their fears.  Both sides are now hoping the laboratory would provide interesting information on how their ancestors lived, what they ate and what they looked like.

Respecting the remains of people from the past was paramount, said Prof Matisoo-Smith. An ultra-clean environment had to be preserved to ensure ancient DNA samples were not contaminated.

In just a year after opening, an international team of researchers, which includes University of Otago archaeologists Chris Jacomb and Richard Walter, successfully isolated ancient DNA from eggshells of extinct birds.

Previous attempts to recover DNA from fossil eggshell have been unsuccessful. Chris Jacomb said, “this new ability to isolate ancient DNA from moa eggshell opens up exciting new research possibilities not just for palaeobiologists, but also for archaeologists. Indeed, it was this potential to address important questions in New Zealand archaeology that drew Associate Professor Walter and me into this international collaboration.”

Using the DNA from the moa’s provides a powerful new tool in understanding how the demise of moa occurred. “Not only can we now match eggshell to particular moa species, we can develop detailed models of hunting practice by looking at the family relationships of individual birds. This will help us understand hunting and extinction processes.”

Back in the 1700s, the best way to determine who a persons father was, was by taking a good hard look at the child, followed by a good hard look at the father. If there were enough coincidences then maybe a relationship could be possible. by the 1800s, it was discovered that eye color could be a paternity identifier. With recent DNA advances we have learned that the eye color theory is flawed. We now know that eye colour is determined by at least six different alleles, or genetic markers. Fortunately paternity testing has become a lot easier and much more affordable over the past few years due to advances in DNA science.

Although an estimated 200,000 DNA tests are conducted each year by states needing to determine child-support and welfare issues, not as many people are willing to conduct their own at-home paternity test because they don’t realize the simplicity and convenience of an at-home paternity test.

How does home DNA testing work?

Paternity testing requires a painless sample from both the child and possible father. Even without a sample from the mother, DNA paternity test results are up to 99.9% accurate. Most companies provide testing material which they will mail directly to you so that you can provide the samples.

Because of advances in DNA testing it is no longer necessary to draw blood. Buccal (mouth) swabs are the standard. These swabs have the same genetic information that is carried in blood but none of the hazards. By gently massaging the inside of the child’s mouth, cheek cells are collected. These cells are then sent to the lab for testing. Labs analyze up to sixteen genetic markers of the child and match them against the markers of the alleged father. Because each of us receives half our genetic markers from each parent, the results of DNA paternity testing are still accurate without the DNA information of the mother but a really good test will include the mother this helps insure that there is no chance of a false positive.

What else can a DNA test do?

DNA test kits can also be used to analyze sibling relationships, establish cousin or grandparent relationships, determine twin zygosity (i.e. whether twins are fraternal or identical), identify ancestral origin, verify Native American decent, assure parents they left the hospital with the right baby, and most important, provide legal evidence – be prepared to pay a bit more for legal tests. Legal tests can be used to settle adoption issues, settle child-support disputes, and provide information for immigration files. Legal tests can not be preformed using a home test kit.

How to choose a DNA laboratory

  • Accreditation is a vital part of choosing a laboratory. Accredited labs have an annual audit and inspection, undergo internal and external reviews, and have their equipment calibrated for accuracy. Look for an ISO and/or AABB certification. Accredited labs will have a good reputation and near 100% track record for court cases.
  • Make sure you understand all the fees.  Keep an eye out for hidden fees. Some companies will charge you for the kit and then charge you again for the results.  This is especially true of kits purchased at a pharmacy or store.
  • Double check when you order your kit that you’re only buying the results you need.  If you need a test for any official purpose (changing a name or birth certificate) Make sure you are getting a legal test.
  • Ask about privacy. Make sure that your identity and intentions are kept secure.

Enjoy piece of mind. Be confident that the questions you have can be answered and that DNA testing is safe easy and stress-free.

Success Rates for DNA Extraction from Non-Standard Samples

In my previous post, we looked at some of the more common types non-standard samples used to obtain DNA from an individual for DNA testing purposes. In this article we will look at DNA how successful a laboratory can be extracting DNA profiles from the various types of samples and how these can vary from one sample to another.

It is possible to fail to obtain sufficient DNA from a buccal swab, for reasons such as:  the swabbing was not adequately performed, the swabs grow mold due to damp storage conditions, bacteria destroys a damp sample or a person just does not give off much DNA during the swabbing process. These cases are rare and problems with this type of sample are normally less than 2%.

Non standard samples, however, can present a greater problem when exacting DNA to create a profile.  Laboratories cannot guarantee that a DNA profile will be obtained from any sample submitted.  Depending on the nature of the sample, there are differing probabilities of success in extracting DNA from each type of sample (in some cases a percentage probability of success is provided).  For the purpose of this article we have broken the samples in to three categories, High, Medium and Low.

High (80% average can be higher or lower) : Samples such as finger nail or toe nail clippings, fresh blood stains or hairs with root  and follicle where, for a qualified and experienced DNA laboratory, extracting DNA is considered relatively straightforward. In such cases, as long as the sample is handled properly both during collection and delivery to the laboratory, one can expect a high probability of success in extracting DNA.

Medium (50%-60% average can be higher or lower) : Samples such as a toothbrush or cigarette butts -  the success rate is influenced by a number of variables including heavy use vs light use and/or storage conditions etc. Therefore a heavily smoked cigarette butt found in an ashtray at home is more likely to result in a successful DNA extraction than a lightly smoked cigarette that has been thrown on the street and exposed to the elements, such as terrain, wind and moisture or rain.

Low (20% – 30% average can be higher or lower) Samples such as teeth or bone, where extracting DNA is a relatively difficult and time consuming process, these normally need to be handled by a highly specialized laboratory, such as ours. In these cases, the individual should consult the laboratory first to check their level of expertise, if they will accept the sample and the cost.

The classification above is however only a guideline, since as we have seen it is not just the type of sample that is important but also other variables can have an influence such as :

1. Poor storage conditions (e.g. damp environment, extreme heat,  etc.).

2. Poor sample handling (possible contamination with other DNA or dirt by touching the sample).

3. Not enough DNA present (e.g. heavily used toothbrush vs used once only).

4. Age of the sample. DNA will degrade over time.

It is also important to note that the success rate will also depend heavily on the ability of the laboratory performing the test. Not all laboratories that can perform DNA Paternity testing on normal swabs are capable of obtaining DNA from a wide variety of non-standard sample. The more difficult the sample (e.g. teeth and bone), the greater the specialization and experience required to increase the chance of a successful DNA extraction. It is important to make sure that that lab that is performing the work is accredited to do so.

Finally, it is also important to note that with non-standard samples there is always a risk that the extraction will not work. Therefore any person considering submitting such a sample, especially where it may be only a limited sample available (e.g. person is dead), should take this into consideration. Selection of an experienced laboratory (possibly of forensic specialization) will help minimize this risk by educating you on the best sample to submit so that you do not waste both time and money.

For more information, please call our company directly.

DNA  Testing is the most accurate way of confirming biological relationships between individuals. The standard way of collecting samples from the people to be tested is through the use of oral swabs that collect cell called buccal cells. Oral swabs are relatively easy to use and pain-free since the procedure involves simply rubbing the swab on the inside of the mouth to collect a cheek cell sample. The swabs can be easily sent by mail to the client when they order a test or from a different country. Swabs provide an excellent medium to obtain DNA from an individual.

However, occasions arise when it is not possible to obtain the sample directly from the individual using a cheek swab. Some examples of  such situations would be: in a case with a deceased or missing person, conducting testing without a person’s knowledge, or samples collected from a crime scene. In these such cases, it is possible to utilize alternative samples (also called non-standard samples), to obtain the DNA of a person for the purpose of DNA Testing.

The following list provides information about a number of non-standard samples that can be used to obtain DNA for testing purposes:

1. Direct Biological Samples

Hair

Any hair submitted must have roots (the hair follicle) attached. Hair that is cut will not produce significant DNA that will allow a standard 16 marker test. When submitting a hair sample, one must make sure not to touch the part with the follicle as much as possible to avoid contamination. The hair can be sent in a normal plastic or paper envelope and marked clearly as a non-standard sample. The lab will normally require a minimum of 6-10 hairs (or as many as possible) depending on what is available. The more the hairs available, the more the chance of obtaining a DNA profile from them. The hair follicle will quickly degrade and, therefore, it is best to send the hair for testing as soon as possible after taking it from the head.

Blood

Blood samples can take various forms including whole blood, blood spots on paper or other material (tissues, clothing, and furniture), dried blood etc.  The best blood sample will be placed on an FTA card. An FTA Cards contain chemicals that lyse cells, which denature proteins and protect nucleic acids from nucleases, oxidative, and UV damage. FTA Cards rapidly inactivate organisms, including bloodborne pathogens, and prevent the growth of bacteria and other microorganisms. This card Blood used to be the most common form of submitting DNA samples for DNA paternity testing until the advent of buccal swabs. It now rarely requested as it is an invasive procedure as compared to the non-invasive and painless nature of a buccal swab. In most cases, these cards are used by Medical Examiners and Coroner Offices to ship a blood sample.

Fresh blood sent in a normal tube will provide a more than necessary sample for obtaining DNA. In cases where blood is sent as spots on some form of material, then the success of the extraction will depend on the state of the blood and whether it has been exposed to possible contamination such as the elements, human contamination and/or chemical agents.

Nails

It is also possible to extract DNA from Nails. Freshly trimmed nails work best and have the highest chance of success. Nails are normally recommended (apart from hair) in cases where the person has recently passed away. It is important to handle the nails with minimal direct contact as possible to avoid contamination. The nails can be sent in a normal plastic or paper envelope and marked clearly as a non-standard sample. The reason nails are better than hair is that the DNA is preserved in the fingernail, which is alredy dead, and will take a very long time to degrade after being clipped from the hand, unlike a hair follicle, which will rapidly decay as it dies.

Sperm

In the case of liquid semen, it is recommended that the sample is absorbed through a clean cotton swab, or sterile cloth and air-dried for about one hour. In the case of dried semen stains, either send the material with the semen directly to the laboratory or absorb the semen stain onto a clean cotton swab that has been moistened with distilled water. The sample should air-dry for about an hour. The samples can then be sent in sent in a normal paper envelope and marked clearly as a non-standard sample.

Bone

Bone samples are one of the most difficult materials to obtain DNA from and, although we do, not all DNA laboratories offer this service. The success rate will depend on the condition of the bones (e.g. how long the person has been dead, how his body has been preserved etc). When submitting bone samples it is normally recommend that fragments from the shaft of the femur or humerus are obtained weighing approximately 2 grams per individual. It is recommended that the laboratory processing the sample is contacted prior to taking the samples to discuss the case in advance. Collection of samples should be performed by a qualified person.

2. Everyday items that may contain DNA for testing purposes

Cigarette Butt

Cigarette butts can be an excellent source of DNA if the sample has not been contaminated. The more the cigarette has been smoked the more DNA is likely to be available. If the cigarette has been shared it is likely that a mixed DNA profile will be obtained, in which case more specialised analysis will be required to separate the profiles. The client should make sure that the sample is not handled from the end used to inhale the smoke. Ideally the client will submit 2-4 cigarette butts if available. The butt can be sent in a normal plastic or paper envelope and marked clearly as a non-standard sample.

Toothbrush

A toothbrush can be a good source of DNA if the sample has not been contaminated. The more the toothbrush has been used the more DNA is likely to be available. If the toothbrush has been shared it is possible that a mixed DNA profile will be obtained in which case more specialised analysis will be required. The client should make sure that the sample is not handled from the end of the bristles to avoid contamination. Also the brush should be air dried for about 30-60 minutes to ensure that it is properly dried before sending to the laboratory. The toothbrush can be sent in a normal paper envelope and marked clearly as a non-standard sample.

Envelope and Stamp

Licked envelopes and stamps can provide a source of DNA for paternity testing purposes. However, the success rate on this type of sample can very widely since it is not always possible to know if the stamp and envelope have been licked or not. In cases where there has been no contact with a person’s saliva then it is clearly not possible to obtain DNA. Because of this, the sample is normally classified as having a low rate of extraction success rate. When submitting the sample, it is important to ensure not to touch the seals and the back of the stamp to minimise possible contamination.

Chewing Gum

Chewing gum can be a good source of DNA if the sample has not been contaminated by exposure to contaminating agents. Sugar free gum is preferred to normal type of gum. It is important to try not to touch the gum with the fingers as this can lead to contamination. The gum can be sent in a normal plastic or paper envelope and marked clearly as a non-standard sample.

If you have other samples that you think might work, such as ear wax or dirty tissues, please contact us for more information about how to submit these items and what the success rate is for these items.

By Alex Blake

DNA testing is done for a variety of  reasons. DNA evidence can link an alleged criminal to a crime scene.  DNA paternity and maternity testing can identify a child’s father or mother. DNA relationship testing can determine if two individuals are from the same family. DNA ancestry testing can determine ethnic origins and genealogical roots.

How DNA testing is done depends on the what kind of results are desired and on what types of samples are available. DNA fingerprinting (or profiling as it’s also known) is the process of analyzing and comparing two different DNA samples. Only identical twins have the exact same DNA sequence, everyone else’s DNA is unique. This makes DNA the perfect way to link individuals to each other or to locations where they have been.

The entire DNA chain is incredibly long, much to long to examine all of it in one test. Human DNA is made up of about 3.3 billion pairs. The differences between DNA samples occur only in small segments of the DNA–the rest of the DNA is pretty much the same. DNA testing focuses on those segments that are known to differ from person to person.

As DNA testing has evolved over time, the testing methods have become more precise and are able to work with much smaller DNA samples. Early DNA testing was done using dime-size drops of blood. Today’s tests can extract DNA from a drinking container. The DNA is extracted from whatever sample is provided (some times there is not enough DNA to provide for testing). DNA must be isolated and purified before it can be compared. In essence, it has to be “unlocked” from the cell in which it exists. The cell walls are usually dissolved with a detergent. Proteins in the cell are digested by enzymes. After this process, the DNA is purified, concentrated, and then tested.

DNA testing is done most often today by using a process called “short tandem repeats,” or STR. Human DNA has several regions of repeated sequences. These regions are found in the same place on the DNA chain, but the repeated sequences are different for each individual. The “short” tandem repeats (repeated sequences of two to five base pairs in length) have been proven to provide excellent DNA profiling results. STR is highly accurate–the chance of misidentification being one in several billion.