Firstly, we adapted and established a published 48-hour RT-QuIC protocol, including the in-house production of recombinant α-synuclein (rec α-syn), and evaluated its sensitivity and specificity through a blinded screening of an 81 CSF sample cohort consisting of Parkinson’s disease (PD), dementia with Lewy bodies (DLB), Alzheimer’s disease, motor neuron disease, multiple system atrophy, unidentified neurodegenerative diseases, and healthy controls. The gene discussed is SNCA; the disease is early-onset autosomal dominant Alzheimer disease.