Explain why Huntington disease is caused by a dominant allele.

The huntington disease is a disease that is caused by the dominent allele. It is the disease which causes damage to the brain cell. The mother and father can be carrier or affected by the disease. As in the condition if both parents exhibit a hetrozygous condition that is both have a dominent as well as as a recessive allele responsible for the disease. Then there is 75% chances of occurence of disease in the child. If both parents are homozygous that is both have dominent alleles then 100% chances of occurrence of the disease.