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Hemochromatosis and the plague

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Plague bacteria shown in a fluorescent antibody test. (Photo: CDC/File)

In a earlier post on AAAS MemberCentral, I discussed a recent study which sought to uncover the genome of the bubonic plague, or Black Death. The long-term suspicion that the implicated pathogen was Yersinia pestis was largely confirmed.

Though it is well known that the plague was responsible for the deaths of nearly half of the European population at the time, evidence also suggests that it may be responsible for the high rates of a disease called hemochromatosis; a disease of excessive iron storage, that "is the most common inherited single gene disorder in people of Northern and Western European descent."

How the most common mutation responsible for hemochromatosis (C282Y in HFE gene) causes disease is only partially understood. One factor that is known for certain however, is that the mutation is responsible for an increased absorption of iron from the gastrointestinal tract.

It is believed that the mutation results in the absence of the C282Y protein on host cell surfaces, causing an increase in the affinity of cellular receptors for transferrin (an unaffected protein in humans which carries iron in the blood) and hindering transferrin acquisition by pathogens. Yersinia pestis, like other iron-hungry bacteria, thrives in an iron rich environment. And it is thus postulated that young Europeans who were not yet stricken by the later problems of hemochromatosis were able to fend-off the bubonic plague by absorbing all of the iron and keeping it in cells, leaving little for the pathogen.

This survival advantage during the plague is thought to be responsible for the current high rates of the mutation in those with European ancestry. If true, this mutation may have been responsible for an increased survival during the plague, but at the cost of a decreased life expectancy for them later on.

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