Question

Huntington's disease is caused by the allele h, which is completely dominant to the normal recessive allele h. consider a couple where the man has the genotype hh, and the woman has the genotype hh. what is the chance that their child will develop huntington's disease?

Answer 1

Thr genotypes of the parents are Hh heterozygote (the father) and hh recessive homozygote (the mother).
The father has a dominant allele (H) that causes him to develop Huntington disease.
As you can see in the punnet square presented below, he will pass this H allele to a half of his offspring, giving them Huntington's disease too.
So, the possibility of the offspring of this couple having Huntington's disease is 50%.