The dominant Huntington disease allele causes severe neural/brain damage at approximately age 40.A female whose mother has Huntington disease marries a male whose parents are normal.It is not known if the female has the disease.Keeping in mind that the disease allele is rare in the population, what is the probability that their firstborn will inherit the gene that causes Huntington disease?

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Quizplus · Accepted Answer

Since Huntington's disease is caused by a dominant allele, a person needs only one copy of the allele to have the disease. The female's mother has the disease, so the female has a 50% chance of having inherited the disease allele from her mother. The male's parents are normal, which means he most likely does not carry the allele (assuming it is rare in the population and neither parent has the disease). Therefore, if the female is a carrier (50% chance), their child would have a 50% chance of inheriting the allele from her. Multiplying these probabilities (0.5 * 0.5) gives a 25% chance that their firstborn will inherit the gene.

The Dominant Huntington Disease Allele Causes Severe Neural/brain Damage at Approximately