SNCA and Parkinson disease: For example, in one recent study typical α-synuclein seeding activity on RT-QuIC distinguished PD from MSA, CBD, and PSP with a sensitivity of 91.4% and specificity 97.5%, whereas a combination of α-synuclein RT-QuIC positivity and NfL below a certain threshold achieved a sensitivity of 98.3% and specificity of 95.8% and a greater area under the receiver operating characteristic curve (Quadalti et al., 2021).