DNA Testing

By | Wikis

DNA Testing

DNA testing refers to a multitude of different tests that use DNA to provide information. DNA is present in every cell of every living organism and is inherited by offspring from their parents. These two facts are what allow DNA testing to provide us with valuable information.

DNA testing can be used to provide information on paternity, genetic risk for disease, identifying individuals in forensics, identifying an organisms’ species, testing an individual’s genealogy, and testing for infection. It is used in a variety of situations, including hospitals, forensic labs, science labs, and even at home, with the use of home paternity testing kits.

Over time, the number of uses for DNA testing has increased, as DNA testing technologies have advanced, and scientific understanding of genetics has advanced alongside it.

Paternity DNA testing

Paternity testing is the use of DNA tests to determine if one individual is the biological parent of another individual

In humans, this of course only needs to be done to determine if a person is the father of a child or not. However, in scientific research on animals, the same process can be used to determine both the mother (maternity testing) and the father.

Paternity tests can also be used to determine the father of an unborn child, by drawing blood from the mother, which contains DNA from the foetus. This can occur any time after the foetus is seven weeks old. This procedure has replaced old techniques that involved inserting a needle into the womb, which can cause miscarriage to occur.

Paternity test

Paternity test

Paternity tests that are performed after birth, however, use cells taken from the inside of the cheek, which are called buccal cells. These buccal cells are collected by rubbing the inside of the cheek with a swab.

 The earliest paternity tests were highly inaccurate! 

They were based solely on the blood type of the two individuals involved. They worked by testing to see which blood type each had, which could be either type A, type B, type AB, or type O. The reasoning behind this is that an individual’s blood type is inherited from their parents.

However, the only result that this type of testing can give is to say whether or not it is possible that the two individuals are father and child. If the blood group of the child is one that is possible to have been inherited from the potential father, he may be the father. If the blood group of the child cannot possibly have come from the potential father, it can be said with certainty that he is not the father.

red blood cells compatibility chart

Blood cells compatibility chart

However, the only result that this type of testing can give is to say whether or not it is possible that the two individuals are father and child. If the blood group of the child is one that is possible to have been inherited from the potential father, he may be the father. If the blood group of the child cannot possibly have come from the potential father, it can be said with certainty that he is not the father.

Paternity testing has massively increased in accuracy since its beginnings, however. First, this was done by comparing white blood cells from the two individuals, which could give information on whether or not they were closely related. It could not, however, be used to distinguish the father from a close relative.

 Since the advent of using PCR, paternity testing has become 99.99% accurate.  

PCR stands for a polymerase chain reaction and is a process that is used to increase the amount of DNA in a sample.

It is, essentially, a repeating reaction that involves two strands of DNA splitting apart and then repairing the lost strand, with this process being repeated thousands of times. The standard procedure for paternity testing is now to use PCR to increase the amount of DNA collected during the cheek swab. This is the fastest, cheapest, and most reliable method of paternity testing, hence its use.

The main use of paternity testing is to allow men to determine if a child is biologically theirs if there is any doubt over parentage. It can also be used in court cases to prove that a man is the father of a child, for him to be obliged to pay child support.

Another, more recently emerged use of paternity testing and maternity testing is to prove that the children of immigrants are their children. This is requested by the immigration authorities of some countries that have large amounts of immigrants, including the UK, the USA, and France. This is requested when the family does not possess records such as birth certificates that prove that they are related.

Disease risk

Another common use of DNA testing is to determine disease risk. Some people are predisposed to suffering from certain diseases due to their genes. There are also some diseases, such as Huntington’s disease, which are directly caused by genes. These genes can be detected by using DNA testing.

A sample of DNA is taken from the individual and PCR is used to increase the amount of DNA in the sample. Then the sample can be tested to see if it contains a copy of the gene that causes the risk or disease that is being tested for. This is usually done by medical professionals in hospitals, but there are now many companies that offer this kind of DNA testing, using self-collected DNA samples taken at home.

DNA testing is to determine disease risk

As well as being used to inform people about diseases and risk factors they are likely to suffer from, DNA testing can also be used by prospective parents. This will allow them to determine if either of them carries genes that could cause health problems in their children. As these health risks and diseases are caused by genes, they are of course inherited from parents.

DNA testing can be used by prospective parents to decide whether or not to have a child. It can also be used to prevent their children from inheriting the gene, by testing the DNA of embryos. This can be used when the parents use IVF, which involves eggs being removed from the mother and fertilized by the father’s sperm, and then implanting the resulting embryo into the mother’s womb. If the embryos are DNA tested before implantation, an embryo that doesn’t carry the detrimental gene can be selected.

There is also a new field of science called nutrigenomics which is centered around the interaction genes have with nutrition and health. This field has arisen because people’s genes affect the way they react to different foods, and can be the source of intolerances to certain foods.

For example, lactose intolerance occurs because sufferers don’t have the gene to produce lactase, the enzyme which digests lactose. This leads to suffering discomfort if dairy products are consumed, as dairy products contain lactose.

If this lactose isn’t digested, bacteria in the gut will ferment it, which causes great discomfort to the person. There are now companies that provide DNA testing to produce information about a person’s genes and how this affects their nutrition and health. These can be used to inform the person about what foods they can’t tolerate well and can inform them of any foods that are likely to be big risk factors for them.


The use of DNA testing in forensics is known as DNA fingerprinting or DNA profiling. It is used to match people to samples of DNA collected at crime scenes. Because DNA is unique to each person, other than identical twins, this allows the identification of people who were present at a crime scene. This allows the identification of criminals and other people implicated in a crime, just by testing the DNA of DNA samples they left at the crime scene.

DNA samples can come from a variety of sources. It can come from blood left behind, or from saliva, which can easily be left on utensils and glasses. Another common source of DNA samples is hairs, which can easily be left behind at a crime scene.

DNA fingerprinting or DNA profiling

What is a DNA fingerprint? | Image Credit: yourgenome.org

Many criminals take precautions to avoid leaving DNA behind at a crime scene, for example by wearing a hat to prevent leaving hairs behind, but it is very difficult to leave no DNA trace at all. And, due to PCR, even a tiny trace of DNA can be tested, by multiplying it to produce an amount great enough for testing. In this way the whole DNA sample doesn’t need to be used for testing, some of it can be kept for evidence, in case it is needed in the future, for example in a court case.

One way of identifying individuals from DNA samples is to take a sample of DNA from them and compare it to the DNA sample. However, this requires the person already being a suspect, or else investigators won’t know who they are. It also requires finding the suspect, which may not be easy if they have gone on the run. Another method of identifying the owner of a DNA sample is by testing the sample and comparing it to a DNA database.

DNA databases are kept by governments, and store information about all DNA samples that are found at crime scenes, along with all DNA samples taken from suspects. When known, the DNA in the database will be matched to the identity of the owner of the DNA.

This allows DNA samples from crime scenes to be matched to previous crimes, and potentially to a suspect. Storing information about DNA in DNA databases also allows criminals to be caught many years later if they are caught for another crime, and their DNA is sampled and tested against the database. In this way, many criminals who aren’t caught at the time of committing the crime, are caught later on.

However, the use of DNA testing in forensics isn’t perfect. It has been shown that artificial DNA can be created in a lab, and this could be used to create false DNA evidence. DNA information can be obtained from a DNA database and that DNA can be artificially constructed, which could be used to plant false evidence.

This obviously has implications for the use of DNA testing to provide evidence in court cases. It is possible to differentiate between naturally produced and artificially produced DNA, as natural DNA contains methyl groups. A methyl group is a part of a molecule that consists of one carbon atom with three hydrogen atoms bonded to it.

Whilst natural DNA contains methyl groups, artificially constructed DNA does not. This means that the presence or absence of methyl groups can be used to determine whether or not a DNA sample has been produced artificially. However, not many police departments currently use this test, meaning they could be deceived by artificially produced DNA.

DNA barcoding

DNA testing can be used to determine what species a sample of DNA has come from. This is commonly used in scientific research, mainly within the field of zoology. There are many ways that DNA barcoding can be used. IT can be used to identify a species that can’t be identified from its physiology. This can occur when plants do not currently have flowers or when insect larvae are more difficult to distinguish than their adult forms.

DNA Barcoding

DNA Barcoding

It can also be used to determine what an animal has eaten, by taking DNA samples from the contents of its stomach or its feces. Another, very important, use of DNA barcoding is the identification of animal parts that come from endangered animal species, such as ivory from rhinos.

DNA barcoding works on the premise that there are large differences in the DNA of different species. It uses sequences of DNA that remain the same between individuals, unlike DNA fingerprinting. This allows DNA samples to be taken from organisms, or from traces of them, and be matched to a species using a database. There are many different databases available, such as the barcode of life database. The barcode of life database contains the DNA of over 190,000 species, which have come from over 2.5 million individual DNA samples.

Genealogy testing

Genealogy testing uses DNA to determine a person’s genealogy. A person’s genealogy is their ancestral history, essentially, who and where they are descended from. Genealogy testing can be used to determine where in the world a person has descended from, which is often impossible by any other means.

This is done by looking for specific DNA markers which are associated with people from particular areas. This shows which current ethnic groups a person is related to, and this allows inference of where they are descended from.

DNA Genealogy

This is done by looking for specific DNA markers which are associated with people from particular areas. This shows which current ethnic groups a person is related to, and this allows inference of where they are descended from.

There are many companies that offer the service of genealogy testing.

 The most popular company is Ancestry.com, which claims to have had over 2 million customers. 

People get genealogy tests out of personal interest, especially if they don’t know much about their family history.

There are also a few medical applications to genealogy testing. This is because some ethnic groups are associated with a higher incidence of certain diseases. This means that the results of a genealogy test may be able to inform people about any disposition they may have to certain diseases. This information may be useful in avoiding further risk factors or seeking medical advice.

Disease detection

Another use of DNA testing, which is rather uncommon, is for the detecting of diseases. While DNA testing is commonly used to detect genes that cause disease risk, its use for detecting diseases that are currently being suffered from is used only in rare cases.

 One such case is the detection of HIV. 

HIV is very difficult to detect, and it used to be detected by testing for antibodies for the virus, which is present in the blood.

However, these antibodies aren’t present until several weeks after infection occurs. This method is even more ineffective in newborn babies, as the antibodies can be masked by the presence of maternal antibodies, which are received from the mother. DNA testing can now be used to detect the presence of HIV viruses.

This can be done by using PCR on a blood sample to increase the amount of DNA from the virus so that it reaches detectable levels. By using this method, it is possible to detect tiny amounts of the virus, as tiny as one viral cell per 50,000 blood cells. This new technique allows the diagnosis to occur much earlier, which then allows the earlier onset of treatment.

It also allows people infected with HIV to make sure they don’t pass on the infection to anyone else, which they could do if they were unaware of being infected. Another useful application of this test is that it can be used to test donated blood. This prevents patients from being given blood that is infected with HIV. It also means that the blood donor can be informed that they are infected with HIV. This test also allows newborn babies to be tested for HIV without interference from the maternal antibodies.


  1. http://www.nejm.org/doi/full/10.1056/NEJMc1113044
  2. https://www.nutrigenomix.com/faq
  3. http://www.independent.co.uk/life-style/health-and-families/features/dna-diet-the-genetic-test-that-alerts-you-to-potentially-deadly-effects-of-salt-caffeine-or-9973704.html
  4. http://www.bbc.co.uk/news/science-environment-30285581
  5. https://dna.ancestry.co.uk/

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