A genetics question: Tay-Sachs disease is a rare human disease in which toxic substances accumulate in nerve cells. The recessive allele is inherited in a simple Mendelian manner. A woman is planning to marry her first cousin, but the couple discovers that their shared grandfather's sister died in infancy of Tay-Sachs disease.

What is the probability that the cousins' first child will have Tay-Sachs disease, assuming that all people who marry into the family are homozygous normal?

I'll draw the pedigree I have and the work I've done - can't seem to get the right answer, though.

Question

A genetics question: Tay-Sachs disease is a rare human disease in which toxic substances accumulate in nerve cells. The recessive allele is inherited in a simple Mendelian manner. A woman is planning to marry her first cousin, but the couple discovers that their shared grandfather's sister died in infancy of Tay-Sachs disease.

What is the probability that the cousins' first child will have Tay-Sachs disease, assuming that all people who marry into the family are homozygous normal?

I'll draw the pedigree I have and the work I've done - can't seem to get the right answer, though.

anonymous · Answer

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