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Genetic / Evolution

Early in the last century, English physician Archibald Garrod noticed that about half the albinos he saw in the course of his practice were the children of first cousins who had married each other. In almost all of the cases of albinism that he saw, whether or not the parents were related to each other, both of the parents were normall pigmented.

a) What is the most likely mode of inheritance of albinism in humans?
b) Suppose you married your cousin. Would your children be albino? Explain.
c) Suppose you want to calculate the frequency of the albinism allele in the English population, based on Garrod's data. Would you be able to apply the second part of the Hardy-Weinberg Law? Why or Why not?

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Early in the last century, English physician Archibald Garrod noticed that about half the albinos he saw in the course of his practice were the children of first cousins who had married each other. In almost all of the cases of albinism that he saw, whether or not the parents were related to each other, both of the parents were normal pigmented.

a) What is the most likely mode of inheritance of albinism in humans?

Response: Since we know that two phenotypically normal parents produce albino children, we can safely assume that the two parents must be heterozygotes. In other words, they are "carriers" for the albino allele. They have one normal allele that produces normal pigmentation and they have one mutant allele that does not produce any pigment. Therefore, when the two carriers mate, 1/4 of the children (on average) will be albino. This is a classic example of an autosomal recessive mode of inheritance. Autosomal means that the gene ...

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