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    Huntington's Disease

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    The son of a man who does not have Huntington's develops Huntington's after age 50. His son develops Huntington's in his late thirties.

    Explain (1) three ways someone can manifest an autosomal dominant phenotype when his father didn't have it, and (2) why this man's own offspring would show symptoms so much earlier than his father.

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    https://brainmass.com/biology/genetics/huntingtons-disease-414270

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    (1) three ways someone can manifest an autosomal dominant phenotype when his father didn't have it

    I think this is somewhat of a trick question. I can think of several ways, but only the first is the "obvious" answer.

    1. The son has an autosomal dominant phenotype because he inherited it from his mother, not his father. If a trait is dominant, you can inherit it even if only one of your parents has the trait (in contrast to a recessive trait, in which both parents need to have it).

    2. A random mutation. Maybe a ...

    Solution Summary

    The expert explains three ways someone can manifest an autosomal dominant phenotype when his father didn't have it. Why this man's own offspring would show symptoms so much earlier than his father are explained.

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