At a high school level and so that is not marked as plagiarism or written by AI answer the following question about Alzheimer's disease: A 23 year old man has 3 biological grandparents who have Alzheimer's. despite his young age, he is worried he will have the disease some day and had genetic testing which found he has 2 mutated copies of the gene presenilin-2. what is the percentage chance he will get this disease? explain.