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Genetics may bear blame for some gum diseases (2/7/97)

Dental researchers led by San Antonian Kenneth Kornman, DDS, PhD, have shown that up to 30 percent of the population may be genetically susceptible to developing severe periodontal disease.

The findings, published in the January issue of the *Journal of Clinical Periodontology*, point to a method of early identification and treatment of at-risk patients.

"This is the first time a genetic factor has been identified for a common disease, affecting such a large segment of the population," said Dr. Kornman, chief scientific officer of the San Antonio branch of Medical Science Systems, Inc., and clinical professor of periodontics at The University of Texas Health Science Center at San Antonio.

Periodontal (gum) diseases result from a bacterial infection of gums and bone surrounding the teeth. Once these bacteria take hold, the body releases a series of chemicals to fight them. This reaction, called an inflammatory response, can result in red and swollen gums, easy bleeding during brushing or flossing, bone loss and many other symptoms. If too many of these chemicals are released, this inflammation can be severe, resulting in advanced loss of gum and bone structure and an increased risk of tooth loss.

The study identified those patients who, when infected with the disease-causing bacteria, are at risk for releasing too many of these chemicals, making them six times more likely to develop severe periodontal disease.

"This genetic identification has the potential to be used as a preventive measure, identifying people before they even show signs of the disease and getting them into early interventive treatment, most likely with a periodontist," Dr. Kornman said.

The researchers, including periodontists and geneticists, reported that the genotype identified in this study occurred in 29.1 percent of northern European Caucasian subjects of unknown periodontal disease status and no other known medical conditions.

In the study, 134 subjects were divided by the severity of their periodontal disease: mild to moderate, moderate and severe. All subjects were free of any other chronic disease as well as cleared for pregnancy and anti-inflammatory drug use.

Subjects were evaluated on the state of their periodontal disease by calibrated examiners and broken into the three groups. A genetic test, via a finger-stick blood test, was then administered.

After eliminating smokers, who are already recognized as being at increased risk for periodontal disease, statistical analysis revealed that more than 60 percent of non-smokers with severe periodontal disease and more than 30 percent of non-smokers with moderate periodontal disease tested positive for this genotype.

Severe disease in subjects who tested negative for the genotype was pronounced only after age 60, whereas the disease was present and severe in subjects 20 years younger who tested positive.

Study subjects were all of northern European Caucasian descent to reduce any differences in the genotypes. "We anticipate, based on preliminary data from other ethnic populations, that these genetic factors will have a similar effect in other ethnic groups," Dr. Kornman said. "We have studies in progress in other ethnic populations to make sure this question is addressed."

Does the new study mean that people should toss out the toothbrush and floss because their dental health is predetermined by their genes? Emphatically not, according to Robert Ferris, DDS, PhD, president of the American Academy of Periodontology. "Actually, the opposite is true. If you test positive for this genotype, it's in your best interest to keep your teeth very clean and to ask your dentist or periodontist to help you prevent the disease." Also, poor oral hygiene can always lead to dental problems, even in individuals without the predisposing genes.

Contact: Mike Lawrence (210) 567-2570