I suspect that my mom developing a tremor is what turned her DRD, which was in retrospect similar to what myself and my grandma have, into Parkinson's. As far as I can tell, for my family anyway, developing the a tremor will rapidly deplete what little Dopamine we can produce and lead to normal'ish looking Parkinson's.

The genetic defects associated with this are I believe a spectrum though, and we happen to be close to one side of it. If you have any symptoms related to DRD, I would see a movement disorder specialist and ask for a trial of carbo/levo. It'll be immediately obvious if it helps, and if you don't have any problems with Dopamine production it won't do anything (except for some mild side effects).