Question

the following individual has huntington disease. what is his genotype? (hint: it is an autosomal dominant disorder.)

Explanation:

Since Huntington's disease is an autosomal dominant disorder, having at least one dominant allele (\(H\)) will result in the disease. The individual has the disease, so they must have at least one \(H\). The fact that they have an offspring without the disease (who would have genotype \(hh\)) means they must have passed on an \(h\) allele. So their genotype cannot be \(HH\) (because then they couldn't pass on an \(h\)). But if we didn't know about the offspring, just knowing it's a dominant disorder, a person with the disease could be \(HH\) or \(Hh\). However, considering the offspring without the disease (who gets \(h\) from this parent), the parent must be \(Hh\).

Answer:

C. \(Hh\)