The role of complexin 1 appears to extend beyond monogenic synucleinopathy cases into sporadic PD, in view of (1) its accumulation in mass-spectrometry proteomics of PD midbrain autopsies, (2) the GWAS meta-analyses of risk loci for sporadic PD, and (3) our findings of CPLX1 blood level downregulation in RBD cases. This evidence concerns the gene CPLX1 and Parkinson disease.