Saliva is one of the most accessible of our body's bio-fluids making saliva sample collection easy and non-invasive. Saliva also harbours a wide spectrum of genetic data that can be used for genetic research and clinical diagnostic applications. It might surprise you to know that much confusion surrounds the source of genomic DNA in saliva. It certainly came as a surprise to me when I met with a number of customers on a recent trip across the continent.
In recent years, we've seen a marked increase in the desire to understand the genetic basis of disease as a means to improve patient diagnosis and treatment. While the range of research spans the spectrum of known diseases, all genetic research projects share one vital building block in that they require DNA as a starting point. Traditionally, DNA has been extracted from white blood cells extracted from whole blood. White blood cells are an excellent source of large amounts of high quality genomic DNA. However, because of the invasiveness and cost of obtaining, transporting and processing blood samples, researchers and clinicians have long searched for alternative methods. Over the past few years, saliva has become recognized as a very important and reliable alternative to blood samples for genetic research, clinical diagnostics, pharmacogenomics and more. What exactly is it that makes saliva such a good alternative to blood for genetic applications? It all comes down to the source of DNA in saliva.
Surprisingly, many people I spoke with assumed the source of DNA in saliva is strictly buccal epithelial cells, however, studies show that up to 74%(1) of the DNA in saliva comes from white blood cells. Yielding virtually the same amount of DNA per volume and the same DNA quality, saliva can be considered as good and as reliable a source of DNA for a wide variety of genetic applications. One thing to note however is that not all oral samples are equal.
Oral Sample Collection Methods
There are three methods for collecting oral DNA samples - dry, wet and non-invasive procedures.
Dry procedures require the donor to insert a cytobrush, buccal swabs or other collection device into the mouth where tissue is scraped from the gum and cheek surfaces. These methods collect primarily buccal cells that are lower quality and are potentially contaminated with bacteria from the teeth and other surfaces.
Wet procedures include swishing liquids in the mouth and spitting them into a collecting vessel. Mouthwash, which can contain a high percentage of alcohol content, is typically used for this procedure. The protocol, which can request the donor to swish for up to one minute, can burn and be uncomfortable for the donor. Mouthwash is also designed to remove bacteria from teeth and other mouth surfaces which results in a high amount of bacterial content being released into the sample.
Both the dry and wet methods described above do not prevent bacteria from growing in the sample and do not actively stabilize DNA. These methods also involve the insertion of an object or substance into the mouth. While it is arguably less invasive than venipuncture, it does not quite meet the definition of ‘non-invasive'.
Completely non-invasive collection using Oragene•DNA is a simple, painless procedure that requires the donor to spit into a collection device. After providing a sample and closing the device, a solution is released from the cap to mix with the saliva. This solution stabilizes the DNA for long-term storage at room temperature and prevents bacterial contamination. There is no requirement to insert an object or substance into the mouth - the user simply holds the tube and spits into it. In my opinion, that's the true definition of non-invasive DNA collection. As we like to say at DNA Genotek, "Just Spit, That's It!"
The high quality and high quantity of DNA collected with Oragene•DNA provides an excellent option for applications ranging from the largest molecular epidemiologic studies in remote locations, to bio-banking or HLA typing and even a single personalized medicine test.
Did anything in this article surprise you? Leave us a comment and let us know.
Interested in learning more about non-invasive DNA sample collection with Oragene•DNA? Register for our live webinar on April 21, 2010 at 11:00am ET.
References: (1) Thiede, C. et al. Buccal swabs but not mouthwash samples can be used to obtain pretransplant DNA fingerprints from recipients of allogeneic bone marrow transplant. (2000). Bone Marrow Transplantation. 25(5): 575-577.)
This morning, Clinical Reference Laboratory (CRL) announced that it has completed validation testing of DNA Genotek's Oragene•DNA saliva collection kits and will adopt Oragene•DNA for use with its molecular diagnostic services.
CRL is a CLIA-certified molecular diagnostics services provider based in Lenexa, Kansas offering a wide assortment of molecular diagnostic services including gene expression profiling, microarrays, CNV/SNP typing, pathogen detection, infectious disease testing, pharmacogenetic testing, sample banking, assays for personalized medicine and custom diagnostics. CRL also operates a global clinical trials division.
"Working with DNA Genotek and utilizing its products enhances CRL's menu of high quality molecular services through saliva-based DNA tests", said CRL Executive Director of Molecular Diagnostics, Dr. Heather Newkirk. "Offering services integrating the Oragene•DNA product allows us to provide our clients with a state of the art solution for extraction and genotyping DNA from saliva. We are impressed with the quality and quantity of DNA we obtain using Oragene•DNA."
"CRL joins a growing list of genomic service providers and technology vendors that have validated Oragene•DNA with their products and/or service offerings," said Ian Curry, president and CEO, DNA Genotek, Inc. "Adding CRL to our program gives our customers increased access to an approved service provider that can reliably process samples collected with our products. Our customers can benefit from CRL's offerings for saliva-based DNA extraction, analysis and testing."
Everyone at DNA Genotek welcomes CRL to the DNA Genotek Partner Program.
For the second year in a row, DNA Genotek will be collecting DNA samples onsite at the National Walk for Epilepsy on March 27th, 2010 in Washington, DC. Our participation in this event supports the efforts of the Columbia University Family Studies in Epilepsy Program and their study which is designed to identify genes that play a role in causing epilepsy.
The National Walk for Epilepsy is the largest of its kind nationally that is dedicated to increasing awareness of epilepsy and raising funds to support epilepsy programs, education, advocacy and research. The venue attracts more than 8,000 participants who are personally invested in helping find a cure for the condition and presents an excellent opportunity for Columbia University to accelerate its research by providing access to significant numbers of candidates who satisfy donor profile requirements.
This scale of onsite DNA collection would not be possible without our Oragene•DNA self collection kit. Oragene•DNA enables easy and non-invasive self-collection of saliva samples from large numbers of people and delivers high quality DNA. The samples remain stable at room temperature for 5 years enabling our customers to collect hundreds or even thousands of samples at an event like this and not have to worry about the storage temperature or degradation in quality of the sample.
This event is part of our DNA Genotek Helping Hands Program which is designed to assist organizations that are innovators in disease research, disease prevention and treatment. Within this program, we apply our technology and expertise to accelerate DNA sample collection or treatment and prevention of disease. The goal of the program is to help our customers' research and advance the fight against disease across the globe.
This year, I will personally be on-site for this collection event and I couldn't be more excited. As the event unfolds, I will update you on the status of the collection, tell you what I experienced and share what I learned.
We're hoping for a record turn out at the ‘Give a Spit' booth and you can help. You can join the hundreds of families that participate in this research program and make a critical contribution to understanding the causes of certain seizure types. Families and scientists, working together, can find the causes of epilepsy and improve treatment.
So if you happen to be in the Washington, DC area on March 27th, drop by the National Walk for Epilepsy and come to the ‘Give a Spit' booth. You can find us on Jefferson Street (between 12th and 14th).
To learn more about the Family Studies in Epilepsy at Columbia University, visit their Web site.
Recent statistics suggest cancer mortality rates are declining due to better prevention, early detection methods and improved treatments, yet so much remains to be done. With cutting-edge research continually pushing the boundaries of science and discovery, it is not surprising that an increasing number of cancer researchers are turning to the newest tool in the DNA collection toolbox - DNA from saliva.
Saliva has traditionally been overlooked as a source of DNA for cancer research but Oragene•DNA has changed that. What makes saliva-based DNA collection with Oragene•DNA so important to cancer research? Saliva provides a non-invasive means of collecting high quality and quantity DNA that is stable at room temperature, which makes samples easy to collect, store and ship. With geographically dispersed subjects, scientists can even mail Oragene•DNA kits to participants, who follow the directions, and return the saliva samples to the laboratory for analysis using standard mail service. Cancer research groups around the world are now focusing on the potential of this common bodily fluid for detecting the genetic link to the disease and studying genes without the need for a blood draw.
Now that researchers trust that DNA from saliva using Oragene is equivalent to DNA from blood, the door is open to populations they would normally not have access to. Collecting blood is very invasive and not a practical procedure for children or individuals that can't give blood for religious or medical reasons or for those who do not have access to a collection center. Compliance rates improve with saliva resulting in the collection of more samples.
Breast cancer researchers at the University of Arkansas for Medical Sciences (UAMS) are hoping to answer some important questions with DNA from saliva. They are building a repository aimed at studying breast cancer risk and treatment. Their goal is to collect 40,000 samples over a five year period. They want to learn why one individual is affected by breast cancer but another is not. Or why two women with the same disease respond differently to the same treatment. What inherited factors contribute to the disease? What environmental factors contribute to breast cancer? How do inherited and environmental factors interact to cause the disease?
The researchers decided to use Oragene•DNA because saliva-based collection offered them a non-invasive, easy-to-use and reliable method to collect the large number of DNA samples they need. The kit stabilizes DNA at room temperature until it can be analyzed, which eliminates storage and logistical issues. In addition, Oragene•DNA provides the high quality, high quantity DNA required for establishing the bio-repository. The reliability and ease-of-use also enabled on site event-based collections bolstering the donor group by thousands in a single day.
In another example, researchers at Inserm (I'Institut national de la santé et de la recherché medicale) in France are conducting a study on thyroid cancer using Oragene•DNA. The primary goal of the project is to better understand the risk factors associated with the development of thyroid cancer. The project will establish a DNA bank to permit future studies of candidate genes linked with thyroid cancer and to study gene-environment interactions. The team evaluated the possibility of collecting blood samples, buccal swabs or Oragene•DNA. After evaluating all options, they decided to use Oragene•DNA as it was the only method that allowed them to overcome their main challenge of maximizing compliance rates for geographically dispersed participants.
So, is saliva-based DNA collection the newest tool in the fight against cancer? Enabled by Oragene•DNA, the answer is a definitive ‘yes'. Cancer research with saliva DNA has definitely come of age.
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