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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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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