H man Genetic Disease
Human Genetic Disease
Today’s questions: How do patterns of inheritance
and natural selection affect human genetic
disease?
I.
Transmission genetics of human disease
II
Selection dynamics of CF
II.
III. Selection on late
‐
onset illnesses
IV
G
i
t i t
ti
i it d
IV. Gene x environment interactions revisited
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I.Transmission genetics of human disease
A. Selection against recessive alleles
M
(
t)
i
ll l
h
l
f f
ti
Many (or most) recessive alleles have loss
‐
of
‐
function or
knock
‐
out mutations—they do not
Why do heterozygotes have a
II. Selection dynamics of CF alleles
Observation 1: CF alleles are at a frequency of about 2%
in populations of Northern European ancestry. Given
the strength of selection against individuals with the
disease phenotype, this is
very
high–even though
Observation 2:
Salmonella typhi
enters gut cells
through the CF gene product. This event starts an
infection and may lead to
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Hypothesis: Individuals who are heterozygous for the CF
disease allele areprotected against typhoid fever.
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- Spring '09
- BRADSHAW
- Biology, Genetics, DNA, recessive alleles, gene x environment, human genetic disease, CF disease allele, CF allele products, CF gene product.
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