In the in vitro binding assay study, using a tritium labeled compound, [3H]HY-2-15, revealed that HY-2-15 has high binding affinities for α-syn aggregations in MSA and PD postmortem brain tissues as well as for misfolded tau proteins in AD, PSP, and CBD brain tissue homogenates. The gene discussed is MAPT; the disease is Parkinson disease.