Hardy -Weinberg equilibrium occurs under the following parameters:
large population size;
no mutation;
no migration;
no selection;
random mating.
The Hardy-Weinberg proportion for sex-linked traits are p (normal
phenotype) and q (affected phenotype) for the males and p^2 (normal
phenotype), 2pq (normal carrier phenotype) and q^2 (affected phenotype)
for the females (assuming one gene with two alleles) (^2 = squared).
The only way there can be a "slight shift" in the HW proportions is if
the allele frequencies alter. By removing the q males and the q^2
females the shift is unkown until we know what the allele frequencies
are, but then we are no longer in Hardy-Weinberg equilibrium because
there is extreme selection against these two genotypes (see above).
The frequency of q males is 1/5,000 births for Haemophilia A and 1/30,000
for Haemophilia B in the U.K. (Connor,J.M. and Ferguson-Smith,M.A. 1984,
Essential Medical Genetics, Blackwell Scientific Publications).
Steven Projan wrote:
> Jabriol wrote:
>> > so if we get rid..uh.. isolate every hemophiliac in the world, and
> > casra...uh
> > nuterize them.. would we remove the defective gene
>> No: as is the case with most all recessive traits there may be a
> slight shift in what is called the "Hardy-Weinberg equilibrium"
> (which is reallly for autosomal recessive, not sex linked, traits)
> but only to the extent that hemophiliacs now have children (which
> accounts for a small percentage of the transmission of the gene).
> This is true even though the defective gene (coding for clotting
> factor 8) for most hemophiliacs is found on the X chromosome making
> this a "sex linked" characteristic (meaning that male offspring of a
> heterozygous mother have a 50% of being hemophiliacs).
>> Remember Queen Victoria? The Tsaravich? Rasputin? Don't we teach
> this stuff in high school anymore?
>> The only way to remove such a gene from the population is for both
> hemophiliacs and carriers of the trait to refrain from procreating.
> While this may sound like a good idea where do we draw the line on
> this kind of practice for inherited traits? Homosexuality? Baldness?
> Votes for Republicans?
>> Het, I'm a bacteriologist, what do I know?
>> Steve Projan
> Wyeth-Ayerst Labs
--
Clinton Hale,
School of Genetics and Human Variation,
La Trobe University,
Bundoora, Victoria, 3083,
Australia.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Phone +61 (0)3 9479 2256
Fax +61 (0)3 9479 2480
Email c.hale at gen.latrobe.edu.au
URL http://www.gen.latrobe.edu.au/microscopy
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
