FIG4 and Parkinson disease: The abnormal vacuoles detected in the fibroblasts of two related patients with aggressive asymmetric CMT4J harboring the same FIG4 genotype (I41T and a nonsense mutation) were shown to represent enlarged dysfunctional late endosomes and lysosomes [25] These findings led researchers to suggest impaired endosomal/lysosomal and synaptic function through physical obstruction of intracellular organelle trafficking, pathways that are already implicated in other genetic forms of parkinsonism.