aSyn seeds are readily apparent in early PD when subjects within 2 years of diagnosis who had not started medications from the Parkinson’s Progression Marker Initiative were studied [166, 167], and high rates of positivity are also observed in prodromal patients with REM sleep behavior disorder and pure autonomic failure, conditions which have a high likelihood of underlying alpha-synuclein and phenoconverting into PD or DLB [165, 168–170]. The gene discussed is SNCA; the disease is Parkinson disease.