Paternity Testing on Absent Fathers

DNA testing is one of the most conclusive ways available to determine paternity of any given child. By taking a sample of DNA from both the alleged father and from the child in question, high-tech DNA profiling techniques are used to match reference points across genetic markers on both samples which can lead to an accurate determination of where a genetic relationship exists.

In an ideal world, paternity testing would have available both a sample from the child and from his alleged father in order to best establish the link between them. However, in some DNA paternity testing cases the father is not available to give his DNA sample, whether through choice, or unavailability for some other reason. However, where the father is absent, it is still possible to use other DNA tests to determine whether a relationship exists.

DNA Testing on Other Direct Relatives

By performing DNA testing with other members of the family that share some of the same genes with the alleged father, it is possible to determine whether or not there is a likelihood of paternity over the child in question. Obviously the father’s sample is desired for reasons of accuracy and conclusivity, however it is more than possible (particularly with advancing testing technologies) to be able to determine paternity through shared genetic material through more distant relatives to the father. In other words, provided a relative of the alleged father is available for DNA testing, you should be able to obtain some results although this may not always be conclusive.

DNA Testing on Grandparents

In the absence of the alleged father or any separate sample of his DNA, the alleged paternal grandparents can provide the key to establishing paternity. By taking a sample from either one or both the grandmother and grandfather of the baby, it is possible to determine even in the absence of the father whether or not there is shared genetic material and consequently whether or not there is a shared relationship, i.e. parentage.

DNA Testing on Male Relatives

Y-STR testing is one of the most innovative DNA testing methods honed in recent years, tracking down the male-only Y- chromosome to establish genetic links between male children and elder vertical male relatives, for example grandfathers, great grandfathers, even great uncles by blood relationships. This can be particularly handy where the father is unavailable and direct elderly relatives have died, given that a great deal of genetic material passes unmutated from father to son throughout generations. Of course, this is however absolutely of no use for DNA testing of female children.

DNA Testing on Siblings

Alternatively siblings can also provide a close genetic match, which makes it possible to test whether or not two children are related by the whole blood, rather than half. Where there is dispute over the potential father of a child, an alleged sibling’s sample can be a good way to compare DNA to determine the extent of the relationship. The same can be said for brothers and sisters of the alleged father, who can also share some genetic material sufficient to provide a result in DNA testing of the child in question,

If your situation requires is such that you require to do the DNA testing through one of the alternatives above, it is always advisable to contact in advance the company who will be performing the DNA test and explain your case in full so that they can advise you on the DNA testing options available as well the results that can be obtained.

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Five Top Things to Know About a Dna Paternity Test

Whilst the awareness about DNA Paternity testing has greatly increased throughout most of the world, there is still a lot of information about the test that is not known.

The following are the five top things to know about a DNA Paternity Test:

1. Most accurate method of determining biological relationships

A DNA Paternity test is the most accurate way of determining a biological relationship between an alleged father/mother and their child. Whilst in the past blood grouping analysis was used as a screening method, the relevance of this test has been greatly reduced as the level of accuracy of this type of test is low compared to the result of a DNA test. A DNA paternity test will provide 100% certainty of exclusion and 99.9%+ probability of inclusion.

2. Difference between an At-Home Paternity Test and a Legal Paternity Test

The difference between an At-Home Paternity Test (also called Curiosity Test) and a Legal Paternity Test is not the actual result but the way in which the sample collection is performed. For an At-Home Paternity test, a home dna kit is normally sent to the requesting party. The kit will normally include i) oral swabs to take the saliva sample, ii) documentation to provide relevant information including consent iii) instructions and terms and conditions of sale. The sample is taken by the parties themselves who are participating in the test. In a Legal DNA Paternity Test, the sample collection must follow a strict chain of custody procedure. All samples need to be collected and documented by a independent third party (normally a qualified general practitioner or nurse) who will be responsible to verify and authenticate the samples. The actual result of the paternity in terms of the biological relationship will not differ.

3. Always select a properly accredited laboratory

Always chose to do your paternity test through a company that uses an ISO17025 and/or AABB accredited laboratory. This will ensure the quality and accuracy of the results. Also make sure that when report the result a full DNA profile is provided for the 16 loci analysed, as well as the statistical probability of paternity. A simple Yes/No answer should not be deemed acceptable.

4. Paternity tests can be performed without the sample of the mother

To perform a DNA Paternity test the sample of the Mother is not necessary to obtain an accurate result. However, when available, it is always recommended that the sample of the Mother is also provided. Only in specific cases will the sample of the mother provide more accurate results such in the case of gene mutation. Many companies offer to test the mother at no extra charge.

5. DNA can be obtained from a diverse range of samples

It is possible to obtain DNA from a number of other sources such as hair, blood, semen and items such as cigarette butts and a toothbrush. Whilst the current standard is to use an oral swab to collect saliva samples, in cases where a person may not be physically present, able or willing to donate a sample, then alternate samples can be obtained.

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Dna Paternity Testing: Submitting Non-standard Samples (part 2)

Success Rates for DNA Extraction from Non-Standard Samples

In part 1 of the article, we looked at some of the more common non-standard samples used to obtain DNA from an individual for DNA testing purposes. In this article we look at DNA extraction success rates from the various types of samples and how these can vary from one sample to another.

Non standard samples do not always guarantee that a DNA Profile will be obtained. Whilst for buccal swabs it is possible not to obtain DNA, such as in cases where the swabbing was not adequately performed or else the swabs grows mould due to damp storage conditions, in general problems with this type of sample are normally less than 2%. Therefore depending on the nature of the sample, there is usually associated a High, Medium or Low probability of success in extracting DNA from each type of sample (in some cases a percentage probability of success is provided).

High (80%) : For samples such as fresh blood stains or hairs with root 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%) : For 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 (e.g. rain).

Low (20% – 30%) For 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 specialised laboratory. In such 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)

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 other media. The more difficult the media (e.g. teeth and bone), the greater the specialisation and experience required to increase the chance of a successful DNA extraction.

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.

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