Saliva Shown To Be As Reliable As Blood For DNA Screening For Genetic Diseases

October 30, 1997

BUFFALO, N.Y. -- A University at Buffalo oral biologist has shown that saliva appears to be as good as blood as a source of genetic material needed to screen people for inherited diseases.

The discovery could simplify the screening process enormously, eliminating the risks and complications of handling, storing and transporting blood, including the risk of contact with blood-borne viruses. It also would allow persons who cannot or will not give blood to be screened, and would be a boon to the needle-phobic.

"This is such a clean, reliable, quick, easy test," said Rob van Schie, Ph.D., a UB post-doctoral associate in the Department of Oral Biology and lead researcher on the discovery. "There are no needles. Samples can be collected by untrained personnel. And it's great for children, because they love to spit."

Forensic scientists have used many materials as a source for DNA evidence, but blood is currently the most commonly used source of DNA for genetic testing, both for clinical use and for basic research, van Schie noted. Unfortunately, the use of blood has many practical disadvantages and inherent limitations.

"Blood sampling is invasive, painful and involves a potential risk of contamination with hepatitis and the human immunodeficiency virus," he stated in his study, published in the October issue of the Journal of Immunological Methods.

"Some patients may be reluctant to submit to phlebotomy procedures on religious or cultural grounds, while others may simply be apprehensive. Hence, an alternative to the use of blood for genetic studies may be desirable."

Van Schie was struck with the idea for the study after hearing a news report on the Unabomber investigation telling of successful DNA analysis of dried saliva from a stamp used by the suspect. At the same time, he was conducting a major research project involving genetic screening of children for potential risk factors for juvenile periodontal disease, a particularly aggressive form of gum disease that tends to run in families. Mark Wilson, Ph.D., formerly of the UB School of Dentistry, is the project leader on that research.

Excited by the possibility of having his young research subjects spit into a test tube instead of being stuck with a needle, van Schie tested the salivary DNA theory using saliva and blood from himself and his wife. Finding the genetic material in the blood and saliva samples indistinguishable, he collected blood and saliva samples from 69 adult volunteers, to test the theory further

Using a procedure called polymerase chain reaction, which replicates tiny pieces of DNA sufficiently to detect minor differences in gene structure, he was able to show that DNA from saliva was as precise as that from blood in revealing polymorphisms in two genes thought to play a role in the development of juvenile periodontal disease.

The results pertain to only two genes whose sequence is known, van Schie noted, and the method has not been proved universally. However, he said, its potential appears very promising.

He predicts that genetic screening for disease will become routine in the near future, a view shared by many, and the subject of a recent editorial in The Journal of the American Medical Association.

Van Schie's findings could increase this momentum, and make genetic testing easily available to populations presently outside the medical mainstream.

The only restriction associated with this method so far? "No French kissing before testing," notes van Schie.

The research was supported by the National Institute of Dental Research.

University at Buffalo

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