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Newswise NEW YORK, NY (March 21, 2014) Researchers at Columbia University Medical Center (CUMC) have devised a new system for classifying periodontal disease based on the genetic signature of affected tissue, rather than on clinical signs and symptoms. The new classification system, the first of its kind, may allow for earlier detection and more individualized treatment of severe periodontitis, before loss of teeth and supportive bone occurs. The findings were published recently in the online edition of the Journal of Dental Research.

Currently, periodontal disease is classified as either chronic or aggressive, based on clinical signs and symptoms, such as severity of gum swelling and extent of bone loss. However, there is much overlap between the two classes, said study leader Panos N. Papapanou, DDS, PhD, professor and chair of oral and diagnostic sciences at the College of Dental Medicine at CUMC. Many patients with severe symptoms can be effectively treated, while others with seemingly less severe infection may continue to lose support around their teeth even after therapy. Basically, we dont know whether a periodontal infection is truly aggressive until severe, irreversible damage has occurred.

Looking for a better way to classify periodontitis, Dr. Papapanou turned to cancer as a model. In recent years, cancer biologists have found that, in some cancers, clues to a tumors aggressiveness and responsiveness to treatment can be found in its genetic signature. To determine if similar patterns could be found in periodontal disease, the CUMC team performed genome-wide expression analyses of diseased gingival (gum) tissue taken from 120 patients with either chronic or aggressive periodontitis. The test group included both males and females ranging in age from 11 to 76 years.

The researchers found that, based on their gene expression signatures, the patients fell into two distinct clusters. The clusters did not align with the currently accepted periodontitis classification, said Dr. Papapanou. However, the two clusters did differ with respect to the extent and severity of periodontitis, with significantly more serious disease in Cluster 2. The study also found higher levels of infection by known oral pathogens, as well as a higher percentage of males, in Cluster 2 than in Cluster 1, in keeping with the well-established observation that severe periodontitis is more common in men than in women.

Our data suggest that molecular profiling of gingival tissues can indeed form the basis for the development of an alternative, pathobiology-based classification of periodontitis that correlates well with the clinical presentation of the disease, said Dr. Papapanou.

The researchers next goal is to conduct a prospective study to validate the new classification systems ability to predict disease outcome. The team also hopes to find simple surrogate biomarkers for the two clusters, as it would be impractical to perform genome-wide testing on every patient.

The new system could offer huge advantages for classifying people with different types of periodontitis. If a patient is found to be highly susceptible to severe periodontitis, we would be justified in using aggressive therapies, even though that person may have subclinical disease, said Dr. Papapanou. Now, we wait years to make this determination, and by then, significant damage to the tooth-supporting structures may have occurred.

The paper is titled, Gingival Tissue Transcriptomes Identify Distinct Periodontitis Phenotypes. The other contributors are M. Kebschull (CUMC), R.T. Demmer (CUMC), B. Grn (University of Linz, Linz, Austria), P. Guarnieri (CUMC), and P. Pavlidis (University of British Columbia, Vancouver, BC, Canada).

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Gene Expression Signature Reveals New Way to Classify Gum Disease

The same gene family that may have helped the human brain become larger and more complex than in any other animal also is linked to the severity of autism, according to new research from the University of Colorado Anschutz Medical Campus.

The gene family is made up of over 270 copies of a segment of DNA called DUF1220. DUF1220 codes for a protein domain -- a specific functionally important segment within a protein. The more copies of a specific DUF1220 subtype a person with autism has, the more severe the symptoms, according to a paper published in the PLoS Genetics.

This association of increasing copy number (dosage) of a gene-coding segment of DNA with increasing severity of autism is a first and suggests a focus for future research into the condition Autism Spectrum Disorder (ASD). ASD is a common behaviorally defined condition whose symptoms can vary widely -- that is why the word "spectrum" is part of the name. One federal study showed that ASD affects one in 88 children.

"Previously, we linked increasing DUF1220 dosage with the evolutionary expansion of the human brain," says James Sikela, PhD, a professor in the Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine. Sikela is the corresponding author of the study that was just published.

"One of the most well-established characteristics of autism is an abnormally rapid brain growth that occurs over the first few years of life. That feature fits very well with our previous work linking more copies of DUF1220 with increasing brain size. This suggests that more copies of DUF1220 may be helpful in certain situations but harmful in others."

The research team found that not only was DUF1220 linked to severity of autism overall, they found that as DUF1220 copy number increased, the severity of each of three main symptoms of the disorder -- social deficits, communicative impairments and repetitive behaviors -- became progressively worse.

In 2012, Sikela was the lead scientist of a multi-university team whose research established the link between DUF1220 and the rapid evolutionary expansion of the human brain. The work also implicated DUF1220 copy number in brain size both in normal populations as well as in microcephaly and macrocephaly (diseases involving brain size abnormalities).

The first author of the autism study, Jack Davis, PhD, who contributed to the project while a postdoctoral fellow in the Sikela lab, has a son with autism and thus had a very personal motivation to seek out the genetic factors that cause autism.

The research by Davis, Sikela and colleagues at the Anschutz campus in Aurora, Colo., focused on the presence of DUF1220 in 170 people with autism.

Strikingly, Davis says, DUF1220 is as common in people who do not have ASD as in people who do. So the link with severity is only in people who have the disorder.

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Gene family linked to brain evolution implicated in severity of autism symptoms