The prion-like spread of αS pathology was studied by Watts and colleagues [121] in the brains of mice hemizygous for a mutant A53T α-synuclein transgene [122] inoculated with αS species from the basal ganglia of two patients with the parkinsonian subtype of multiple system atrophy (MSA), a rare disease with prevalence between 3.4 to 7.8 cases per 100,000 [123], and from an aged control. Here, SNCA is linked to multiple system atrophy.