The Founder Effect: An Interesting Genetic Story
Hereditary hemochromatosis represents a striking example of the "founder effect," which describes a genetic disease that arises from a mutation in just one or a few individuals. In the case of hemochromatosis, it is believed that a single individual in Europe, 60 to 70 generations ago, was the sole origin of most of the hemochromatosis seen in the world today.
A chance mutation in the HFE gene in this individual was passed on, and because the defective gene didn't cause any problems in people through child-bearing age (and may have conferred some benefit in times of nutritional deficit), there was no negative selection to stop it from being passed on. Because of its origin, hemochromatosis today most often affects Caucasians of Northern European descent, although other ethnic groups can be affected by other iron overload diseases.