Researchers find new genetic risk factor for severe CTE
A new study may have uncovered a key genetic factor which makes some more susceptible to chronic traumatic encephalopathy (CTE) and its most severe symptoms.
According to the findings published in the journal Acta Neuropathologica Communications by researchers at the Boston University School of Medicine and the VA Boston Healthcare System, a single gene variant in a gene called TMEM106B may explain why not every individual found to have CTE experienced the more severe symptoms seen in others.
“We know that people can have more or less severe CTE disease even when they’ve had a similar amount of head impacts or contact sports participation. Genetic variation between people might account for some of this difference,” study author Thor Stein, M.D., Ph.D., told CBS News. Stein is a neuropathologist at VA Boston Healthcare System and assistant professor of pathology and laboratory medicine at Boston University School of Medicine.
To come to this conclusion, the team examined the brains and DNA from 86 former football players who were diagnosed with CTE after their deaths.
While the Boston University brain bank has over 600 brains which have been donated by deceased individuals from sports, the military, and elsewhere, the researchers say these 86 brains were the ideal sample to examine the genetic factors for CTE. This is because they experienced similar levels of trauma during their lifetime.
While examining the DNA, the team found two distinct variants of the TMEM106B gene. Approximately 60% of the sample showed the “major” genetic variation of this gene, while the remaining 40% had a “minor” genetic variation.
Those with the major variation were also at least 2.5 times more likely to have experienced severe CTE symptoms and exhibit higher accumulations of p-tau proteins which have been linked to neurodegenerative disorders like Alzheimer’s.
The findings provide a significant clue to a potential trigger for the development of more severe forms of CTE which may resemble Alzheimer’s or Parkinson’s disease. However, it is still unclear exactly how the TMEM106B gene actually factors into this phenomenon. The next step is to further examine the processes that are associated with these variants in the development of CTE.
“Understanding the genetic risk factors might allow us to predict who will be most at risk for disease and therefore who to follow more closely clinically and get treatment when possible,” Stein said. “Genetic risk factors can also provide clues for possible mechanisms that lead to disease and help guide how we might eventually target treatments for CTE. Down the line it may also be helpful to inform individuals before they engage in an activity associated with repetitive head impacts.”
Still, Stein says the biggest predictor of CTE isn’t in someone’s genes.
“The biggest risk factor is environmental, namely repetitive hits to the head.”