Question

Huntington's disease is a genetic disorder that can result in memory loss and abnormal body movements. Huntington's disease results from a defective gene (H) that is dominant to the allele that produces normal function (h). This means that

I. if someone is heterozygous for Huntington's disease, then he/she will be a carrier but will not have the disease.
II. if a child has Huntington's disease, then at least one of his/her parents has the disease.
III. if two parents do not have Huntington's disease, then their children will not have the disease.
I and III only
I, II, and III
II and II

Answer 1

This means that someone who is heterozygous for Huntington's disease will have the disease.

If a child has Huntington's disease, this means that he/she has at least one allele for the disease. The allele had to be passed from one (or both) of his/her parents, so at least one of his/her parents has Huntington's disease.

Since Huntington's disease results from a dominant allele, an individual must be homozygous recessive (hh) to be free from the disease. So, if two parents do not have Huntington's disease, they both must be homozygous recessive (hh), which means they do not have the disease-causing allele to pass onto their children. So, their children will not have Huntington's disease.

Answer 2

so whats the answer?

Answer 3

@Ashlann