How to Interpretate DNA Paternity Test Results

Many people think that a DNA paternity test will give a “yes” or “no” answer. The truth is that it is slightly a bit more complicated than that. In the vast majority of tests, either an “inclusion” or “exclusion” result will be reported.

What an Inclusion Means

An inclusion is reported with a probability of paternity (POP) of 99% or more and a match is found at all genetic markers tested. In an inclusion report, it is stated that the alleged father “cannot be excluded” as being the biological father of the tested child. These three words often create a lot of confusion. This wording is used since an inclusion can not ever be reported at 100%. However, the combined paternity index (CPI) should also be looked at, as it can help to make the results more understandable. First though, it should be understood that the bare minimum for reporting an inclusion result is with a POP of 99% and a CPI of 100 (alleged father and child only) or 500 (alleged father, child and mother). Since our laboratory utilizes an advanced analysis of fifteen genetic markers as a standard, we normally see POPs and CPIs far exceed the minimum requirement. So, when the CPI is say, 100,000, it can be interpreted as a 1 in 100,000 (of the defined male racial population) certainty that the alleged father is the biological father of the tested child.

What an Exclusion Means

An exclusion is reported with a POP of 0.00%. In an exclusion result, it will be seen that at at least two genetic markers, there is a non-match. In an exclusion report, it is stated that the alleged father “was excluded” as being the biological father of the tested child. When an exclusion is reported, a second, independent test will be performed to confirm that the exclusion can be duplicated.

Other Possibilities

Another possible result may be an inclusion with a mutation. In most cases, an inclusion result means that at all tested genetic markers, a match is found. However, sometimes an inclusion can be reported when all but one marker has a match (or, in rare cases, two). Known mutations have a specific frequency in various racial populations and, often, that frequency is low. So, when the mutation frequency is figured into the formula for calculating the POP, it can possibly cause the POP to fall below 99%. To confirm mutations, it is always recommended that the mother test, if she has not already, or to perform extended testing of additional markers.

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Grandparents Can Get Involved With Paternity Testing as Well

Traditionally, we think of paternity testing a something that involves a wronged spouse or a father looking to see if he has a paternal relationship with a particular child, but there are other instances where dna testing is used for the betterment of people as well.

DNA Testing

We’re all familiar with the fact that dna testing is widely used to solve criminal activities as well but one of the places where people might be surprised to find it being implemented is with cases concerning the grandparentage of individuals. Generally, this kind of test is used to determine if two people can be the biological grandparents of a child. Like other kinds of dna testing and including a paternity dna test before birth, this process requires both the consent and samples be collected from all the parties involved.

This is a procedure used to determine the way a family’s relationship works with each other when the father isn’t available for testing. As with the other kinds of dna testing, there’s a need to find these relationships as they pertain to claims that are being made for social security and other inheritance claims.

Reputation

Of course the need for this kind of dna testing generally means that the people involved want to make sure they get in touch with the best facilities that can carry these tests out in a reasonable and timely manner. That’s where reputation means everything to these paternity testing companies. It’s easy to find the best of these places online but there are a few other routes that you can take to ensure that the facility you choose will give you the best service possible. You can check their reputation several ways including:

- Asking friends and relatives what they know.

- Looking on the Internet to see what’s been posted about any particular paternity testing company.

– Asking professionals like lawyers in your community who they use.

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Can I Do a Paternity Test if the Alleged Father is Dead?

DNA testing is the most reliable way of confirming the biological relationship between two individuals. The most widely applied test is the DNA Paternity test whereby an alleged father is tested to confirm whether he is the biological father of a child or not. The test is relatively straightforward to do and involves rubbing oral swabs on the inside of the mouth and submitting it to the laboratory for analysis.

However, there are situations where the alleged father is not available for testing because he has passed away. Many think that in such circumstances there is no solution to this problem and the paternity can never be established conclusively.

In reality, there are a number of options possible for confirming the identity of the father. One of them is through DNA Relationship Testing, which is similar to DNA Paternity Testing but involves testing close members of the family to confirm various types of relationships. Tests can be performed between siblings, uncle/aunt and niece/nephew and grandparents. These tests are beyond the scope of this article but are worth exploring as an option where the father is not available for testing.

In case of death, we will explore three separate scenarios and what the client needs to do in these situations:

Case 1: If the person has just died and it is still possible to obtain biological material from the body (usually this period is not more than one week from time of death), it is recommended that the Client tries to obtain (where possible) hair samples with root as well as fingernail cuttings. A technically qualified laboratory should be able to extract DNA from these samples and use the DNA to perform the paternity comparison.

Case 2: In the event that the body has already been buried, samples may be obtained in an indirect manner – for example through a toothbrush, comb (might contain useful hairs), dentures or recently smoked cigarettes. These samples are all likely to contain DNA material that can be used to perform the test. However, success in obtaining DNA from such samples depend on a number of factors most importantly the condition of the sample and how much DNA it contains (e.g. a fully smoked cigarette vs a relatively unused one.)

Case 3: In cases where the body has been buried for a number of years, and the samples available are skeletal remains, it is recommend that a bone fragment from the shaft of the femur and/or the humerus weighing approximately 2 grams and/or two teeth per individual are obtained.

The above are some of the options available. The most important element is to be able to obtain a sample from the deceased person that may contain DNA. Of course the costs and difficulties in obtaining a sample in Case 3 (e.g. body will require exhumation) are relatively higher than simply obtaining some hair or fingernails from the body. However, each case has its own specifics and one is always advised to seek advice from an expert in this field (e.g. forensic pathologist) or the company that will be used to do the testing.

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Dna Paternity Testing: Submitting Non-standard Samples (part 1)

DNA Paternity testing is the most accurate way of confirming biological relationships between individuals. The standard way of collecting samples from the individuals to be tested is through the use of oral/buccal swabs. Buccal 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 saliva sample. In addition, they can be easily sent by post to the client when they order a test. Hence, they 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, as for example in the case of a dead or missing person or samples collected from a crime scene. Therefore, in such cases, it is possible to utilise alternative samples (defined as 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 or the follicle attached. Hair that is cut will not produce significant DNA. 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.

Blood

Blood samples can take various forms including whole blood, blood spots on paper or other material (tissues, clothing, and furniture), dried blood etc. 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 opposed to the non-invasive and painless nature of a buccal swab. Fresh blood sent in a normal tube will provide a more than enough 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 died. 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.

Sperm

In the case of liquid semen, it is recommended that the sample is absorbed through a clean cotton swab and air-dried for about one hour. In the case of dried semen stains, either send the material directly to the laboratory or else absorb the stain onto a clean cotton swab moistened with distilled water. Then air-dry for about an hour. The samples can then be sent in sent in a normal plastic or 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 not all DNA laboratories offer the 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 plastic or 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.

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The Amelogenin Sex Gene in Dna Paternity Testing

DNA testing is now the most widely used method for determining the biological relationships between individuals. The DNA paternity test is probably the most widely known of these tests and involves the testing of an alleged father, mother and the child in question. This test can also be conducted just between Alleged Father and a child without the Mothers sample.

When performing the Paternity Test, most DNA testing laboratories will test a minimum of 16 genetic markers for enhanced accuracy levels in excess of 99.99%. One of these genes tested is called the ‘Amelogenin’ gene and its use is to determine the sex of the sample that has been processed. Therefore in reality the statistical analysis is actually based on the matching of 15 of these 16 markers.

From a biological perspective, males have an XY chromosome and females have an XX chromosome. Therefore in your DNA test result you should see an XY for the alleged father and the child if he is male, and XX for the Mother and child if she is female. A DNA paternity test result from any serious service provider should report this gene together with the rest of the genetic markers analysed.

Functions and Uses of Testing the Amelogenin Gene

The testing of this gene may appear superfluous to a client at first instance, however it does serve a number of functions.

1. From a laboratory perspective, it acts as a primary quality control check and ensures that the correct samples have been processed. So for example, if the Alleged Father’s sample turns out to be female, then there is an element of quality control to identify the possible reasons. These could include problems such as the client putting the wrong samples in the wrong envelopes (e.g. putting the father’s sample in the mother’s envelope and vice versa). The testing of this gene can also act as a deterrent for submitting someone else’s samples (having said that, this applies only if the sample of someone of the opposite sex is supplied).

2. Gender identification through DNA testing has also got applications in the field of forensic DNA testing as it provides primary information regarding samples found at the scene of the crime during a criminal investigation. Through the test, it is possible to confirm whether biological remains found at the crime scene belong to males or females. It is also possible to differentiate this even in cases of mixed samples.

3. Gender identification is also applicable in the case of infidelity DNA testing. Analysis of the samples will show whether suspicious stains belong to a male or female individual. On the basis of this result, decisions for further testing can be based.

However, gender identification by amplification of the amelogenin gene can sometimes generate a result in which male samples were falsely identified as females. I have myself only seen few of these cases over the years. This occurrence is therefore very rare and occurs in less than 0.01% of cases in males and even less in females according to some studies. In such cases, it is suggested to perform the Y amplification of SRY gene or/and Y-STR markers to confirm the gender

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