LRRK2 and Parkinson disease: We divided sporadic PD, LRRK2 PD participants, and paired demographically matched healthy controls (n = 74 participants) into 5 groups (Supplementary Data 2) for 5-fold cross-validation, where a model is trained to predict healthy or PD on 4 of the 5 sets of the cell line pairs and tested on the held-out 5th set of cell lines (Fig. 5a).