Yes, I think so. From my lab, I know the recent genes we've identified in ALS affect toxicity in our models for Huntington's disease and also our model for Alzheimer's disease. There's a definite crossover. I don't know about Parkinson's because we don't have that in our lab.
It's somewhat surprising, but maybe not. The point is well taken that anything we find in one of these diseases, for the most part, will have a good chance in functioning across other late onset neurogenetic diseases as well.