Special Samples – Submission of non-standard samples for DNA testing
What is the typical type of sample collected?
To understand what qualifies as a special sample it is important to first understand what the common types of samples collected are. The most common type of sample that is collected for paternity/maternity, family relationship, immigration/citizenship or curiosity testing is a cheek swab of the individual(s) in question. The cotton swab collects skin cells from the cheek and saliva. The swab is then rubbed on a Flinders Technology Associates (FTA) card to transfer the biological material to the card which will help stabilize and preserve it until it can be processed. Occasionally, the swab(s) may be directly submitted for testing. Seen less frequently in the situations mentioned above but more commonly in forensic casework is the collection of a blood sample. In these cases, a small amount of the liquid blood is transferred onto an FTA card. When the FTA card arrives at the lab it is sampled by taking a small punch or cut-out from the stained area of the card and placing it in a tube for further processing in order to develop a DNA profile.
What is a Special Sample?
A special sample is considered to be a sample submitted for genetic testing that is not a cheek swab or saliva/blood on an FTA card. This is a very broad category that can encompass many different items but it can be loosely defined as any item that is submitted for testing that is known to or believed to contain genetic material. Since these items are submitted as a substitute for a cheek swab, there needs to be a high degree of certainty that the specific individual has handled or contacted the item in some way to transfer their DNA onto it. These types of items will require a forensic item examination technician for processing using specialized screening techniques in order to collect the DNA for processing. The derived samples are then sent on for DNA extraction, amplification, quantification and analysis in order to develop a DNA profile.
Why would you submit a Special Sample?
The reason a case/project may require a special sample to be submitted can vary depending on the circumstances and information sought after. However, three of the most commonly identified reasons in any of the categories mentioned below are an unwillingness to participate in testing; an individual is unavailable and death.
A paternity or maternity test is conducted to determine who the biological father or mother is of the child in question, and can be requested in either a legal capacity or curiosity inquest. For this test, TheDNALAB typically collects a sample from the alleged father, child, and mother, and in some circumstances, not all parties may be able to or willing to participate in testing. Therefore, in order to obtain a sample of the parent’s or child’s DNA, an alternative source must be identified. Another scenario that may arise for this type of test is that one of the parties is deceased. When this occurs, the standard swab sample is not always an option and alternative biological sample or special sample may be the only way a profile can be obtained.
In order to immigrate to Canada, it may be requested that the biological relationships among family members be verified as part of the application process. This may also be requested of Canadian citizens looking to relocate to a foreign country. Either situation may result in family members who are overseas or sponsors here in Canada needing to be tested. Similar to the paternity scenarios mentioned above, the death of a family member overseas, whether it be recent or historical, can make obtaining a biological sample more of a challenge – though not always a difficult one to solve.
Family Relationships – Legal Testing & Curiosity Testing
Legal testing is carried out when it is likely that the results of the biological testing will be used and possibly contested in legal proceedings at a family, civil, or criminal court level. Situations that lead to curiosity testing include those looking to verify their biological relations for family reunification or for peace of mind. Examples of situations in which legal testing would require the verification of biological relationships include issues surrounding custody (non-immediate family members), estate settlement and aboriginal status/membership. Today, it is becoming more commonly seen that for the settlement of an estate to be completed, those who are to receive inheritance must verify their biological relationship to the deceased. This means that if there is not already a profile on file for the deceased, one must be generated from available sources. Situations where the individual in question is not available to provide a sample in either a curiosity or legal setting can arise. This may mean the individual has been declared missing or contact has been lost and it is not known whether they are deceased. In these cases, in order to establish a familial relationship, an unconventional source of their DNA will need to be collected.
What is important to consider when choosing a special sample?
When it has been established that in order to proceed with testing, a special sample is required, the next stage is to determine what should be submitted. It is important that the item selected contains the DNA of the specific individual, the DNA on this source needs to be as pure as possible and any biological material present must be viable.
Whose DNA is on the item?
Before selecting an item, think about who has used this item. To increase the chance of successfully obtaining a DNA profile, it is best to submit an item that was solely used by the person in question. This reduces the chance of a mixture of two or more individual’s profiles being developed which may not be as helpful as a single source profile. A useful tip to keep in mind is that any time your skin comes in contact with an item, a trace amount of you is left behind on that item. So what does this mean? Consider a case of deciding whether to submit a hairbrush or a toothbrush from an individual who lives in their family home. A hairbrush kept somewhere like a shared bathroom has a greater chance of being used by more than one person or coming in contact in several other ways with additional sources of DNA. All these interactions increase the likelihood of finding more than one person’s profile on the item. Where a toothbrush is generally an item that is not shared – only used by the owner. In this case, the toothbrush would be the better choice to submit for DNA testing.
How often was the item used?
The more an individual has come in contact with an item, the more opportunity their biological material has had to build upon the item creating a better source for testing. Items that are frequently used will contain a greater amount of DNA in comparison to a brand new item. Try to select items that a person would use every day like a watch versus something like a necklace that is only worn on special occasions. The frequency of use does not apply the same to single-use type items. Some examples of single-use type items include bandages, cotton buds, and disposable utensils. For these items, it is unlikely they will be used more than once so instead, consideration should be placed on the length of time since use. It would be ideal to submit a disposable fork that has been used within the last 24 hours than one that was used a week ago. Items that have not been used for an extended period of time have a great chance of any DNA present being degraded reducing the potential for success.
Will the DNA be viable?
This can be thought of as ‘has the object containing the DNA been stored in a way to best preserve it?’ The exposure of DNA to different environmental factors, such as time, temperature, sunlight, and chemical compounds, can have a detrimental impact on the DNA’s quality. As mentioned above, the longer the DNA has sat on an item the greater the chance of degradation. Storage of a sample in a location that experiences dramatic temperature fluctuations will result in the quality of the DNA being negatively affected. An example of this is a garage or a shed. These locations are often not insulated to the same degree as a house so their interiors can feel the temperature rise and fall more intensely. Items from inside these locations like a pair of safety glasses are more likely to have DNA that is damaged. Additionally, direct exposure to sunlight can lead to destructive structural changes in the DNA molecules; if possible, it is always best to avoid items that sit in direct sunlight for extended periods. Lastly, chemical compounds can be found in almost any environment today and can have harmful effects on DNA. Consider if the item selected for testing has recently been exposed to any household cleaners as they can break down the DNA making it unsuitable for testing.
How to collect and package special samples for shipment
Once the item(s) have been selected, the next step is collecting the item and preparing it for shipment to TheDNALAB. It is important to properly collect the samples in a way that preserves and protects the continuity of the biological material as much as possible. Below are some tips to keep in mind:
- When collecting an item to be submitted for testing sterile latex or nitrile gloves should always be worn. This will prevent the collector’s DNA from getting on the item and protect the collector from any material transferring onto them.
- Avoid touching or handling the area that the sample is located on as much as possible.
- Avoid talking over the item or bringing it near your face – prevent contamination.
- Tie back any loose hair to prevent accidental contamination.
Storing the item
- Consult with your customer service representative whether a paper or plastic container is better for DNA preservation and safety.
- If the item being collected is moist or damp allow the item to dry out as much as possible before packaging it. It is best to ship items that are dried as this reduces the risk of mould developing.
- Chose a container that can be securely sealed and ensure it is completely sealed.
- If the object has any sharp edges try to ensure the packaging will be safe for those handling it.
- The exterior packing should be structured enough to protect the object within from damage. It may be necessary to use packing fillers to ensure the inner container stays safe.
- Avoid shipping special samples the day before a long weekend as this will result in them sitting in transit longer than necessary.
- Use a courier or express service to ensure the fastest delivery time and allows for tracking.
- If there will be a longer transit time, adding an ice pack (not loose ice) inside the container will help preserve the DNA.
Special Samples processed in TheDNALAB
Over the past 20 years that TheDNALAB has been in operation, we have been involved in the processing of numerous different types of special samples submitted to the lab. Listed below are some examples of the various special samples that have been submitted in which DNA profile has been successfully obtained.
When a toothbrush is received in the lab, an item examiner uses a sterile razor to remove the bristles from the head of the toothbrush. Then a sterile swab is dampened and the head of the toothbrush and bristle stubs are thoroughly swabbed. The swab head is then placed in a tube and submitted to DNA unit. The head and bristle area are swabbed since this is the portion that likely contains a single source sample and the greatest quantity of DNA. The cut bristles and toothbrush is either returned to the submitter or disposed of upon request.
A plastic disposable razor was submitted as a special sample. The item examiner carefully inspected the razor for any signs of blood-like material but did not find any. It was noted that on the backside of the head there was a build-up of what appeared to be dead skin cells. The examiner then took a sterile swab and moistened it before carefully swabbing the entire front and backside of the razor head. Some of the dead skin cell-like material was transferred onto the swab. The swab was then submitted to the DNA unit.
In another case, an electric razor was received for processing. In the submission notes, it was indicated that this item was packed up from an individual’s place of employment. Keeping this knowledge in mind, the examiner avoided testing the handle area of the razor since it was unknown if gloves were worn when it was collected. It was found the blade face was hinged and could be opened. The backside of the blade face and interior surface was swabbed with a damp sterile swab. It was noted there was hair-like and skin-like material transferred to the swab. That was then sent to DNA unit for processing.
A hearing aid was submitted as a special sample to TheDNALAB. This unit consisted of a behind-the-ear control unit and two earbuds. The item examiner noted yellowish/brown staining on the earbuds that resembled ear wax. A damp sterile swab of each earbud was taken and a DNA profile was successfully developed. The technician avoided taking a sample from the control unit as it is more likely that this section would be handled by more than one individual.
Cotton bud swab (a.k.a. “Q-tip”)
In this case, a cotton swab was submitted with blood-like staining on one bud. The item examiner cut the entire stained bud off and placed it into a sterile tube to submit to DNA. However, when the area of staining or bud end with the biological material cannot be determined additional work is required. The item examiner will have to take both bud ends and submit each for processing independently. This may result in additional charges for the submitter. Therefore, if submitting a cotton swab, when possible, indicate which end the sample is located in a manner that does not compromise the sample. This can be done by using a sterilized knife or scissors to cut off the unused end. Customer service can also assist with suggestions on how to do this.
Straws & Cups
When a straw is submitted, the examiner must determine if it is possible to tell which end was used in the mouth. If this is possible, then a damp sterile swab is taken of ~ 1-2 cm of the area below the opening. If it cannot be determined which end was placed in the mouth, a swab of both ends is taken and submitted for processing. This again may result in additional charges and should be avoided if possible. Always indicate the end used in the mouth when possible.
Used disposable cups have also been sent in. If a cup is received with a lid, then a damp swab of the mouth area and lid tab is taken. If there is no lid present, a swab of ~ 1-2 cm of the outer and inner circumference from the opening is taken.
A pair of glasses were received as a special sample. Using a dampened sterile swab the examiner swabbed both of the nose pads to submit for DNA processing. This area was selected as it regularly is in direct contact with the wearer’s skin and not commonly touched when another person is handling a pair of glasses.
Fingernails/Toenails & Tissue
Generally, the submission of fingernails/toenails and tissue samples are sent by a funeral home or medical professional. These types of samples are usually collected after death. When nail samples are received, they are generally in the form of clippings. Depending on their size, one or a few clippings are directly placed in a tube and submitted for processing. Tissue samples may be received mounted on a microscope slide or as a small portion. When mounted on a slide, the examiner must remove the slide cover and scrap off the fixed tissue using a sterile razor blade. The scrapings are collected and submitted to the DNA unit. When a small portion of tissue is received the examiner cuts off a very small sample, usually ~ 0.5 cm3 or smaller, to submit. Not a lot of tissue is required to generate a profile as long as it is of a good quality.
TheDNALAB has also been involved with processing casework concerning forensic paternity scenarios. One example is the identification of found human remains. In this type of case, human remains are found and a family believes the deceased to be their biological relative. Forensic paternity testing is carried out to see if a biological relationship can be established. The remains may have been too decomposed for traditional sampling so a bone or tooth sample is submitted to the lab. An examiner, with specialized training, assesses the sample to determine the best sampling strategy. The examiner then cleans and dries the bone before submerging it in liquid nitrogen. Once the bone has sat for a period of time the examiner then crushes the sample into a powder form. A portion of this powder is then sent to DNA. Samples are collected from the alleged relatives and once all profiles have been generated a paternity/maternity assessment is carried out.
Types of Special Samples to avoid submitting
• Fecal matter and urine
• Heavily soiled items
• Facial Tissues
• Food items
• Cut hairs
While DNA can be found on a wide variety of items one might come across in daily life, there are certain things which are not ideal to submit for testing. The processing procedures and time required to generate a suitable sample to submit for testing from certain items outweighs the potential of successful processing. This situation would include fecal matter or urine and diaper samples. In these cases, it is likely a more suitable alternative sample could be collected.
Food items generally do not contain large amounts of DNA and are more likely to have DNA that has begun to degrade; decreasing their likelihood of success. This is especially true if the transit time is longer or the item is improperly stored. There is also the possibility that the item itself could start rotting before the lab receives it.
Heavily soiled items are objects with large amounts of staining or containing additional foreign substances on them. The addition of this extra material(s) may overwhelm the limited amount of DNA preventing a profile from being successfully obtained. It is also possible that the foreign material may contain components that interfere with the DNA extraction or amplification procedures used in the lab.
With facial tissues, it can be difficult for the item examiner to locate the exact area of the sample if there is no discolouration present. These types of tissues are also generally very thin and can easily tare, increasing the chances the sample may be lost or contaminated.
Hairs cut from the head do not contain the root, located below the skin’s surface, which holds the majority of the nuclear DNA material. Therefore, there is very little chance cut hairs would have enough DNA to develop a profile.
Questions regarding any aspect of special samples or concerns can be directed to our knowledgeable customer service team at TheDNALab. If you are interested in having any of the types of DNA testing mentioned above, please contact us at TheDNALab.
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