We chose to terminate these experiments at 9 months post injection and it is possible that a longer incubation time after injection of MSA or iLBD brain extracts may have resulted in more severe pathology with sarkosyl-insoluble alpha-synuclein aggregates and clinical signs as observed in M83+/−-mice injected with brain homogenate from MSA patients [61] or wild-type mice injected with synthetic alpha-synuclein fibrils [28, 31]. This evidence concerns the gene SNCA and multiple system atrophy.