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rkoch rkoch
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12 years ago
Duchenne's muscular dystrophy (DMD) is an X-linked genetic disorder.  In human population the DMD allele frequency is approximately 1 in 10,000. The other allele for this gene is a normal wild-type allele. Males can be affected or unaffected, whereas females can be affected, unaffected carriers, or unaffected non-carriers.Among males, what is the frequency of affected individuals?
 Among females what is the frequency of affected individuals?
 Within a population of 100,000 people, what is the expected number of affected males? In the same population, what are the expected number carrier females?
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wrote...
12 years ago
Now your data is complete.
The frequency of disorder (recessive) allele, q(Xa), is 0.0001.
The frequency of normal allele, p(XA) = 0.9999.

In female, the freq of genotypes would be follow Hardy-Weinberg equation:
(p + q)^2 = p^2 + 2pq + q^2, where
p^2 : freq homozygous normal (XAXA)
2pq : freq heterozygous normal (XAXa)
q^2 : freq affected females (XaXa)

In male, the frequencies of normal and affected males are just  the same as the frequencies of normal and disorder alleles, because males only have one X chromosome.

Among males, what is the frequency of affected individuals?
=> 0.0001 (same as the freq of the recessive allele)

Among females what is the frequency of affected individuals?
=> q^2(XaXa) = 0.0001^2 = 0.00000001

Within a population of 100,000 people, what is the expected number of affected males?
=> 1/2 [sex] x 0.0001 [q] x 100000 [pop] = 5

In the same population, what are the expected number carrier females?
=> 1/2 [sex] x (2 x 0.9999 x 0.0001) [2pq] x 100000 [pop] = 10
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