Hemophilia

["MacLellan, Jay" <jay.maclellan@pnl.gov>]

Re:  "I would also say that not all negative mutations are selected

against survival.  There are a number of genetic diseases that do not

improve the species, e.g. hemophilia, but are still present and are

passed along.  It escapes me what was the evolutionary or genetic

process that allowed it to exist in humans."



A mutation does not have to be beneficial to exist in the human gene

pool.  All that is required is that it is not fatal to the individual

until after successful reproduction.  In the case of hemophilia, it is a

recessive trait that can be passed through a generation without being

expressed.  According to my medical dictionary, "It is a sex-linked

hereditary trait, being transmitted by normal heterozygous females who

carry the recessive gene.  It occurs almost exclusively in males."  I

don't believe there are any more evolutionary pressures favoring its

existence, than there are evolutionary pressures in favor of diabetes.

It all comes down to whether you believe our species is evolving toward

perfection, or away from it. 



Jay MacLellan



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