Genetics Probability (Autosomal Recessive)

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    Genetics Probability
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Discussion Overview

The discussion revolves around the probability of offspring having a genetic condition, specifically cystic fibrosis, given that both parents, Jane and Bill, are considered potential carriers. The conversation explores different interpretations of genetic probabilities in the context of autosomal recessive inheritance.

Discussion Character

  • Exploratory, Mathematical reasoning, Debate/contested

Main Points Raised

  • One participant suggests that both Jane and Bill are carriers and proposes a probability of 1/4 (25%) for their child to have cystic fibrosis.
  • Another participant requests clarification on the calculation leading to the 1/4 probability and expresses uncertainty about it.
  • A different participant proposes an alternative probability of 1/9, arguing that Jane and Bill may not be carriers, with a 2/3 chance for each to be a carrier. They calculate the probability as 2/3 X 2/3 X 1/4.
  • One participant expresses agreement with the reasoning of the 1/9 probability, acknowledging that the problem can be tricky.

Areas of Agreement / Disagreement

Participants present competing views on the probability of the child having cystic fibrosis, with no consensus reached on the correct probability. The discussion reflects uncertainty and differing interpretations of the genetic probabilities involved.

Contextual Notes

The discussion includes assumptions about the likelihood of Jane and Bill being carriers and the implications of those assumptions on the calculated probabilities. The calculations presented depend on the definitions and interpretations of carrier status.

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Homework Statement
Jane and Bill are married. Each of them has a brother with cystic fibrosis, which is autosomal recessive. Neither Jane, Bill or any of their parents have the disease. Based on this information, what is the probability that if this couple has a child, the child will have cystic fibrosis?
Relevant Equations
Cystic fibrosis is autosomal recessive.
I think both Jane and Bill are carriers. I'm unsure if the answer is 1/4 (25%).
 
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Why not show the working that leads to your answer of 1/4, and say why you are unsure about it?
 
Wait I think the answer could be 1/9.
It could be possible that Jane and Bill may not be carriers.
There is only 2/3 chance for each to be a carrier.

If both are carriers, then there is a 1/4 chance Jane and Bill's child could have cystic fibrosis.

Multiplying,
2/3 X 2/3 X 1/4 = 1/9
 
I agree with your reasoning.

At first I didn't , it can be tricky.
 
Last edited:

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