I wonder if it can distinguish between PD and PD Plus disorders or multi-system atrophy? I'm sceptical about these markers.

Also, I think there are various causes of PD, so I wonder about their sample of PD patients. For example, even people in the same family with the same LRRK2 gene defect can have different symptoms and different brain pathology, seen at autopsy. Would their metabolites differ, too?