Did evolution give us inflammatory disease?

The research team, led by Philip De Jager, MD, PhD, BWH Department of Neurology, and Barbara Stranger, PhD, University of Chicago looked at genome-wide association studies along with protein-protein interaction networks, as well as other data and found 21 places in the genome that bear a 'signature' for both inflammatory disease susceptibility and natural selection.

Towfique Raj, PhD, BWH Department of Neurology, is the lead author on this study. The findings suggest that in the past these variants rose in frequency in the human population to help protect us against viruses, bacteria and other pathogens. But now in our modern world, the environment and exposure to pathogens has changed, and the genetic variants that were originally meant to protect us, now make an autoimmune reaction more likely. These results are consistent with the hygiene hypothesis in which our cleaner environment is thought to contribute to the increasing prevalence of inflammatory diseases.