September 04, 2010

DNA Testing Guide

The Importance of DNA

DNA (deoxyribonucleic acid) is the genetic blueprint that determines a person's biological characteristics. DNA is located in every nucleated cell of the human body. Except for identical twins, each person's DNA is unique.

Half of your DNA is inherited from your father and the other half from your mother. Siblings (brothers or sisters) can inherit different combinations of DNA from the same parents and are therefore different from each other.

For example:

The technology of DNA profiling is not yet advanced enough to allow for the examination of every single difference between people's DNA. Here at Anglia DNA, we look at specific areas of DNA, which are known to vary widely in length between different people. The process of DNA profiling measures these differences in length. DNA can be extracted from any cells that contain a structure called the nucleus. This includes blood, semen, saliva or hair samples.

How do you take a Paternity Test?

Our paternity test kits contain a series of colour coded swabs and envelopes (pink for mum, blue for dad and yellow for children). The whole procedure is quick, straightforward and painless, and can be done in the privacy of your own home.

Using the swabs provided, you simply rub the head of the swab inside the inner cheek to collect a sample of buccal cells from each individual being tested, place the swab stick inside the collection envelope provided, and return the samples to us in the freepost envelope provided for analysis.

NOTE: If the test is required for legal purposes (such as a court case or amending a birth certificate), a different procedure for sample collection is required - see Legal Test Service below.

How are the samples analysed?

Once the samples arrive here at Anglia DNA, they are booked in under a unique case number. The laboratory testing begins when all the samples in the case, usually taken from the child, mother, and alleged father, have been received.

The samples are then taken into the laboratory, and each undergoes a set of standard analytical procedures, during which the DNA is extracted from the cells and processed in order to obtain a DNA profile from each sample. The results are then passed on to a scientist who has experience in interpreting DNA profiles.

As each person's DNA is inherited from their parents, half from the mother and half from the father, it is therefore possible, by comparing the child's profile with that of the mother, to determine which pieces of DNA in the child's profile have come from the mother.

For example, below is a typical profile at 4 areas of DNA that we look at (we actually check 15):

We can see which parts of the child's DNA come from the Mother (highlighted in pink). The remaining DNA has therefore come from the biological father. If the profile of the alleged father contains these particular pieces of DNA, then it is possible that this man is the child's biological father; if not, then it may be possible to exclude that man as the biological father of the child.

In the above example, we can see that the Alleged Father 1 cannot possibly be the father - his profile does not contain the correct bits of DNA at Area 1 and Area 3, and so he is excluded as being the biological father of the child, even though he does match at Area 2 and Area 4 (highlighted in yellow - the match in these areas is entirely due to chance*). This result is 100% conclusive.

Alleged Father 2 however, does contain a match at all 4 areas to the child (again, highlighted in yellow), and so he is not excluded. The next stage is to calculate how strongly the results favor the alleged father as being the biological father of the child. The results reported are not conclusive, but are likely to provide very strong evidence, resulting in a probability of paternity of around 99.9999%.

This may be reduced in cases where the mother does not take part to 99.0%.

The scientist assigned to the case will interpret the results accordingly, and compile a report.

* some pieces of DNA are more commonly found in the population than others and therefore the match that we are seeing between alleged father 1 and the child in areas 2 and 4 are entirely due to chance, and not indicative of a genetic relationship between these individuals.

The report

Once all of the samples have been received, it takes our team of highly trained scientists approximately 6 days to carry out the test and compile a report. Written reports are issued to the nominated person on the consent form. For an additional fee, we can also issue additional copies of the report if more than one person is nominated on the consent form.

The report will show:

• Details of when the samples were received and from whom
• An explanation of the tests carried out
• An explanation of the results obtained

Depending on the results of the paternity test, the report will conclude either that:

"Based on the results of the DNA analysis, the Alleged Father, (Mr John Smith), IS EXCLUDED as the biological Father of the child (Mr James Smith)."

Or:

"Based on the results of the DNA analysis, the Alleged Father, (Mr John Smith), IS NOT EXCLUDED as the biological Father of the child (Mr James Smith). The genetic testing results obtained give a probability of paternity of XX* %"

* The evidence will be described in terms of its strength. The strength of the evidence is calculated using standard statistical methods which are recognised worldwide in paternity testing laboratories.

Are the results conclusive?

Here at Anglia DNA Services Ltd, we use the latest DNA profiling technology to analyze samples submitted to us.

A result of EXCLUDED (i.e. the alleged father is not the biological father of the child in question), is 100% conclusive.

If a man is NOT EXCLUDED (i.e. the alleged father is likely to be the biological father of the child in question), we calculate how strongly the results favor the alleged father as being the biological father of the child. The results reported are not conclusive, but are likely to provide very strong evidence, resulting in a probability of paternity of around 99.9999%.

This may be reduced in cases where the mother does not take part to 99.0%.

How to choose a company to do the test

The first thing to realise is that 99% of all the legitimate testing companies do exactly the same tests. There are two main brands and as long as they test for at least 15 alleles they should be just as accurate. There are one or two statistical differences between the results to do with the frequency of each allele appearing in the general population, but the laboratory will provide a statistic on how likely it is that any other person could have conceived the child. This is why companies ask for ethnic origin as it affects the statistics since certain frequencies are more likely to occur in certain ethnic populations. You can't actually go as far as working out the ethnic origin from a normal genetic profile there is simply not enough statistical material to give an accurate assessment.

There are two different types of test

1. Self-Sampling tests (ie home tests or private tests)
2. Legal Test Service tests (ie tests for legal purposes)

As far as the work carried out in the laboratory is concerned, the tests are exactly the same. The important difference is that the Legal Test Service tests have a "chain of custody". This means that the sample is collected by a Sampler (who will be a GP, Practice Nurse, or a member of our staff), who confirms the identity of those being tested, and returns the samples directly to us. The process is designed to eliminate the chances of samples being tampered with or the wrong person being tested.

In the case of Self-Sampling tests or home tests, the laboratory has only the signatures on the documents to go by and the laboratory cannot be certain whose DNA is on the swabs. It is up to the participants to carry out the sampling correctly. While this ensures privacy, the results of such testing would not be admissible as evidence in court and could not be used for other legal purposes (such as immigration, amending birth certificates etc).

NB: It is often recommended that where there is significant doubt as to paternity, a Self-Sampling test is carried out first so as to avoid the expense and trouble of the Legal Test Service until the results are more certain.

There are five different types of paternity testing companies

1. The fully ISO 17025 accredited UK based laboratories: These are the highest quality laboratories in the country. All their processes and procedures are monitored by the accreditation body and they are the only laboratories that can produce a report that can be used as legal evidence. It costs tens of thousands of pounds to gain the accreditation and many months of work which is why there are only a few ISO 17025 laboratories doing paternity testing. To carry out court-directed parentage tests laboratories also need to be accredited by the Ministry of Justice (formerly the Department of Constitutional Affairs, and before that the Lord Chancellor’s Department).
2. Overseas ISO 17025 laboratories: While the laboratories maintain an equally high standard of work there is some doubt currently as to whether all tests are considered of evidentiary quality in the U.K. courts. There are several other qualifications and approvals that some hold such as being regulated by the American Association of Blood Banks but these have no relevance to a U.K. court. Any use of their accreditation in validating the information would require dealing with the laboratory direct rather than via a reseller.
3. U.K. non accredited laboratories: There are one or two often associated with a medical facility or a college. As they do not have any laboratory qualification it is difficult to judge the quality of the service.
4. Resellers to U.K. laboratories: Some U.K. laboratories do not like dealing with the public direct and use resellers to market their services. This means that the reseller has a contract with the laboratory which does the testing. They handle the calls and deal with enquiries and pass the samples through to the laboratory. Due to bulk discounts and service level agreements they are often able to provide tests cheaper than the laboratory will offer direct. i.e. RelationChecker is a reseller for Anglia DNA and is in the same building as the laboratory. The actual testing is exactly the same but as Relation Checker is not itself accredited, it cannot carry out tests for legal purposes - such testing must be carried out by Anglia DNA through its Legal Test Service.
5. Resellers to overseas laboratories: There are several companies that simply take in samples and send them to a cheap overseas laboratory. They often claim that the work is ISO 17025 accredited but this is completely invalidated by the fact that the samples pass through a third party’s hands. They are often one man bands operating out of a post-forwarding address. There have been several scandals involving these companies and any claims should be treated with extreme caution.

N.B. Paternity testing is an extremely serious step to take. You should make sure that you can trust and rely on the results as they could have significant affects on your relationships. It is too important to leave to a cowboy company in order to save a possible £20 or £30.

What happens if one party is deceased or missing?

If the person concerned is deceased other samples can be used. (Contrary to what most thriller writers say it is extremely difficult to produce a profile from a hair sample unless the follicle is attached.) But dandruff, chewing gum, false teeth, toothbrushes etc can be used. You will have to deal directly with a laboratory such as Anglia DNA that is experienced in these matters. There are also legal problems to consider such as whether you have the right to send in the samples.

How will the test results affect my relationships?

There is no way to know in advance what affect it will have and most reputable testing companies will be able to put you in touch with a counselor if you feel that it will help. Because the suspicion is already there within the relationship, it will give you the proof one way or another which can allow you to resolve the matter and move forward rather than having nagging doubts for years. The overwhelming response we receive from the thousands of cases we have dealt with is a feeling of relief even if the result was not the one they might have wished for. After all there is more to any relationship between family members than just genetic connections.

What other relationships can you check?

Besides paternity testing, we can check other family relationships such as brothers and sisters. Please contact us for further information as these relationships require different methods of analysis and are more complex than paternity testing.

We hope you have found this guide useful but if you have any further queries or wish to order a test please call us and speak to one of our staff or even the scientists. We have dealt with thousands of tests and almost every conceivable situation and have the experience to be able to give you the confidence to rely on our expertise and efficiency.

Telephone 08454 586587 or 01603 450946 to speak to a member our support staff who work alongside the scientists in our Norwich laboratory. They have dealt with thousands of cases and will treat all your details with the utmost discretion.

You may also find additional information about DNA Testing in the Frequently Asked Questions section on this website.

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