Hemochromatosis tall tales and the HFE gene

Could extra iron in your body help you grow taller? Yes, according to a study cited recently in the New England Journal of Medicine. And taller is better, right? By many accounts it is, bringing greater earning power in many countries (there are a few downsides, so to speak, such as trying to relax in one of today's airline seats).

The tallest people, by country, are the Dutch, followed by the Norwegians, Serbs, and Swedes (if you find this stuff interesting there is a great chart in Wikipedia). The Celts of old, namely the general population of northern Europe several thousand years ago, were notably tall. Julius Caesar wrote that Celts looked with contempt on the short Romans. This fact is noted by the two doctors who carried out recent research on iron overload and height in Switzerland: Increased Height in HFE Hemochromatosis (Pietro E. CippĂ , M.D., Ph.D. and Pierre-Alexandre Krayenbuehl, M.D.).

Their finding? Hereditary hemochromatosis can make you taller. Of course, if you know the problems to which hereditary hemochromatosis, caused by mutations in the HFE gene, can lead, then I doubt that in today's world anyone would choose to have this condition. However, research has discovered a number of "benefits" of HH, to which we can now add increased height. In the case of Swiss males with excess iron and genetic hemochromatosis, this advantage is approximately 1.7 inches (4.3 centimeters). Naturally, that number is an average. My wife has HFE hemochromatosis and is now doubly disgusted because she is actually shorter than average (the article describes how they arrived at this number). Here is what the authors of the study conclude:
On the basis of our clinical observations, we speculate that patients with HFE hemochromatosis may benefit in their first two decades from constantly enhanced iron absorption, providing a steadily sufficient supply of iron during physical development.

The implications of this are truly fascinating because one of the biggest points of debate in HH research is the extent to which the effects of the genetic defect manifest or "express" themselves in people. Put simply, there's a lot of argument about how many people who test positive for HFE defects actually develop iron overload. It would be fascinating to know if the researchers tracked people with HFE defects who had not yet experienced excess iron, but rather enjoyed the benefits. Indeed, what does "excess mean" if the effects are beneficial? When does the condition cross over into being a problem.

The study also helps to explain why HH became so widespread, the most common genetic mutation in people of Western European ancestry. Thousands of years ago, people with HH were potentially better able to survive on diets that were not iron rich. Women who tended to load iron would have been better equipped to survive childbirth, another positive selection factor. We now know that they also gave birth to taller offspring, a further positive selection factor. You can even surmise that young warrior males who frequently lost blood in combat would have been shielded from the onset of iron overload. As for women with HFE hemochromatosis, they tend to experience iron overload later in life, after menopause, but in ancient times many women died before menopause, obscuring the negative impact of their genetic mutation.

One point to bear in mind when reading this study: HH affects a lot of people who don't think of themselves as Celtic in any way, shape, or form. People who self-identify as black or African-American or "person or color" can still have genetic hemochromatosis. Consider the following extract from a study by the Journal of the National Cancer Institute:
Although HFE gene mutations were less common among the African-American subjects than they were among the white subjects, African-Americans who possessed an HFE gene mutation were at greater risk of colon cancer (OR = 2.1, 95% CI = 1.1 to 3.9) than were whites who possessed an HFE gene mutation (OR = 1.2, 95% CI = 0.8 to 1.6).

Read the full article here. Indeed, I have always felt ambivalent about using the term Celtic curse in case it spread the notion that you have to be a blue-eyed blonde to have HH. See my article on President Obama's trip to Ireland for more on this.


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