The growing list of genetic diseases and disorders that are associated with the heterozygote advantage has led many researchers to search for previously-undiscovered connections. This may offer an explanation for why celiac disease appears to be more prevalent today than in years past.
Dr. Bana Jabri director of research at the University of Chicago Celiac Disease Center, and population geneticist Luis B. Barreiro hypothesize that celiac prevalence is tied with increased immune activity that historically could have been a fitness advantage. Both scientists argue that as population density increased due to farming and livestock domestication, human life became “filthy” and having a more active immune system was a fitness advantage as the body tried to fight off a new litany of infectious particles.
Again, there is a tradeoff: an immune system that overreacts to otherwise innocuous substances like gluten.
Celiac does appear to have a genetic basis, and with the ubiquity of wheat in most diets there could be some advantage afforded to those carrying these alleles. Indeed some evidence suggests that these celiac-associated alleles are increasing in frequency, and 40 percent of all Americans are carriers for one of the two most common alleles associated with celiac disease (named HLA-DQ2 or HLA-DQ2).
However, the case might be not as strong as these researchers believe because these celiac-associated alleles behave very differently than those that cause cystic fibrosis and sickle cell anemia.
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