In this context, our finding in MSA serum samples that did not exhibit an increased α‐synuclein similar to PD raises 2 interesting possibilities: One explanation is that in MSA α‐synuclein is not released by neurons in L1CAM‐positive exosomes because it accumulates primarily in oligodendrocytes in the brain. The gene discussed is L1CAM; the disease is multiple system atrophy.