Fischer et al.49suggested that the levodopa monotherapy strategy in PD patients was associated with worse disease outcomes in BDNF rs6265 T carriers while L1CAM exosomal Linc‐POU3F3, L1CAM exosomal α‐syn, and GCase activity could be used to assess the severity of PD.50 Here, L1CAM is linked to Parkinson disease.