Sarah's mother has Huntington's disease, an illness that results from a dominant gene. Her father, on the other hand, does not have the illness. What is the likelihood that Sarah herself will develop the disease?

Question

Quizplus · Accepted Answer

Huntington's disease is caused by a dominant gene, meaning that if a person has one copy of the disease gene, they will develop the disease. Sarah's mother has the disease, so she must have at least one copy of the disease gene. However, since her father does not have the disease, he must have two copies of the healthy gene. So Sarah could inherit either a healthy allele from her father or an allele that produces the illness from her mother, giving her a 50 percent chance of developing the disease.

Sarah's Mother Has Huntington's Disease, an Illness That Results from a Dominant