Staffan Lindeberg wrote on 5/5 in response to a question on hemochromatosis
by Jennie Brand Miller:

>>...If agriculture arose in the Middle East and spread gradually
>>to Europe, why don't Arabs have an even higher prevalence of HH?
>
>Supposedly because that particular mutation never took place in that
>population.

This would be the simplest explanation for the HH mutation that is
predominant among whites. A more general question is whether one might not
expect other kinds of hemochromatosis mutations in other racial/ethinic
groups that have been exposed to agricultural selection. Not necessarily,
but it does seem that the harder iron overload disease is looked for, the
more evident it becomes. It has now been reported as common (though not so
much as the Caucasian form) in both African (1) and Hispanic (2)
populations based on assays involving transferrin saturation (a biochemical
measure). It would be interesting to see a similar analysis carried out on
those of middle eastern descent.

I also want to point out to the group that although I did synthesize the
evolutionary aspect of HH from scratch, I was pretty sure similar ideas had
to be around among HH researchers. They do seem pretty obvious once you're
familiar with hemochromatosis. Sure enough, yesterday I came across a
reference where it is specifically suggested that HH confers a selective
advantage to heterozygotes by protecting against iron deficiency (3), so
not too much credit to me after all. Tracking down this story has got me to
wondering, though, about the extent to which one might be able to paint a
broader theoretical picture about the genetic impact of agriculture by
looking at some of the more common inherited metabolic diseases and trying
to visualize scenarios similar to that for HH.

1) Gordeuk et al (1992) N Engl J Med 326: 95-100.
2) Felitti et al (1996) Morbidity Mortality Weekly Report 45: 991-3.
3) Crawford et al (1995) Am J Human Genet 57(2): 362-7.

Gary