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What is the most common genetic abnormally?

mathog at seqaxp.bio.caltech.edu mathog at seqaxp.bio.caltech.edu
Thu Jun 19 11:59:41 EST 1997

In article <33A8B2F6.4415 at geocities.com>, HH Awareness <c845a at geocities.com> writes:
>Re: What is the most commom genetic abnormally?
>In some cases, such as sickle anemia, the heterozygote (single
>gene) may have a selective advantage in a certain population
>(i.e. greater resistance to malaria) and is therefore selected
>for. Whereas the homozygote (double gene)  is likely to die
>Does anybody know of a selective advantage of being heterozygous
>for hemochromatosis or cystic fibrosis? 

I recall hearing somewhere or other that heterozygotes for cystic fibrosis
have increased fertiility, but do not recall the reference, or even if it 
was in a journal or just the lay press.

The symptoms for hemochromatosis occur quite late in life, especially for
females, in any case, after the child bearing years, and it may well be
that there is very little negative selection.  One can imagine that
hemochromatosis might confer an adaptive advantage earlier in life for
those on a very iron poor diet, but that's just a guess. 


David Mathog
mathog at seqaxp.bio.caltech.edu
Manager, sequence analysis facility, biology division, Caltech 

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