My Husband Was Just Diagnosed With MSA With Orthostatic Hypotension

My husband was just diagnosed with MSA with Orthostatic Hypotension with symptoms of Parkinson's, but the doctor said he doesn't have Parkinson's. His brother has Atrophy of the Cerebellum and a type of Parkinson's Disease. Do they have the same or similar conditions? Does their sister have cause for worry about her future?