Similarly, we observed an association between genetically predicted increased expression of GPNMB and PD in astrocytes (MR—PIVW = 1.02 × 10−8, βIVW = 0.27) and OPCs (PIVW = 1.47 × 10−8, βIVW = 0.15), and this directionality of effect between GPNMB and PD was recently supported by the experimental demonstration that loss of GPNMB activity reduces cellular internalization of fibrillar α-synuclein and related pathogenicity18. The gene discussed is GPNMB; the disease is Parkinson disease.