9 of the instruments showed evidence of eQTL effect size heterogeneity (Cochran’s Q test; P < 0.001) across GTEx tissues, which consisted of rs2945253-FAM863BP and rs2905435-GATA2DA associations with schizophrenia, rs7184567-STX4 and rs858239-GPNMB associations with Parkinson’s disease; rs55667375-PRSS36, rs7097656-TSPAN14, rs4295-ACE and rs56377155-AC012146. This evidence concerns the gene GPNMB and Parkinson disease.