The top four GWAS signals include two well-established protein components of neuropathological features of PD: SNCA (encoding α-synuclein), the major component of Lewy bodies (16) and MAPT (encoding tau), which is present in the form of neurofibrillary tangles in the substantia nigra of roughly 80% of PD patients (17). Here, MAPT is linked to Parkinson disease.