We homogenised and sonicated cerebellum (7 cases of MSA) and substantia nigra (5 cases of PD) from neuropathologically confirmed cases of disease (200 mg/ml) and injected 2.5 μl into the hippocampus and 2.5 μl into the overlying cerebral cortex of heterozygous M83 mice transgenic for human mutant A53T α-synuclein. The gene discussed is SNCA; the disease is multiple system atrophy.