Is Huntington's disease a heterozygous genotype?

Answer 1

Most patients are heterozygous for the mutant copy of huntingtin however in some rare cases there are individuals who are homozygous for the disease-causing allele.

Homozygosity for the disease gene does NOT cause death at the embryo stage as the previous answer stated. Huntingtin null mice show embryonic lethality, but this is when they have no copies of the huntingtin gene at all. This is not the same as being mutant for the gene.

Individuals will have received one copy of the huntingtin gene from each of their parents and so the number of disease-causing CAG repeats will vary between each allele. If both copies have more than 35 repeats then they can be said to be homozygous for the mutant huntingtin allele. This seems to result in more severe symptoms and disease progression.

Answer 2

Huntington's is an autosomal dominant disease, and therefore must be heterozygous at all times, because if it is homozygous dominant, then the potential child, when conceived will die not soon after: the fetus would be greatly disabled. Since Huntington's is in fact dominant, then it is impossible for the trait to be homozygous recessive. In short: if H represents Huntington's, and h represents a normal person, then someone with Huntington's must have the genotype of Hh. A person with Huntington's disease(Hh) A "normal" person H h h Hh hh h Hh hh Lastly, any child conceived to ONE parent has a 50% chance of inheriting the gene, as shown in the Punnet Square Above. -Alexandra Janho

Answer 3

Using the letter H for the dominant trait for huntington's disease and r for the recessive trait, it would be either Hh or HH. That's because HD is autosomal dominant.

Answer 4

No. Huntington's Disease is autosomal dominant.

Answer 5

Plato users,

True.

Answer 6

Yes, autosomal dominant.

Answer 7

Yes