Huntington's disease appears to run in Willy's family. Willy's father was diagnosed with it after Willy was born and, although Willy's mother did not suffer from the disease, Willy has now been diagnosed as having Huntington's disease. Assuming Willy's wife does not have the disease, what percentage chance does their 5-year-old son have of eventually showing signs of Huntington's disease?

Question

Quizplus · Accepted Answer

Huntington's disease is an autosomal dominant disorder, meaning that only one copy of the defective gene, inherited from one parent, is necessary for the disease to occur. Since Willy has the disease, he has one copy of the defective gene. Each of Willy's children has a 50% chance of inheriting the defective gene and thus a 50% chance of developing the disease.

Huntington's Disease Appears to Run in Willy's Family