Like what? You should already have a will, life insurance, etc. even without the disease. All you're doing by knowing earlier is causing psychological harms to yourself and the people you tell, adding more years of anxiety, grief, and sadness for no gain. Think about the bigger picture.
Downsizing your house? Picking your long term care location? Changing your asset balance? Recording more photos, audio, and video?
Knowing an early, painful fate allows you to approach it with dignity.