Increasing expression of agrin, lipoprotein receptor‐related protein 4, muscle‐specific kinase, and rapsyn, improved NMJ formation and reduced denervation in mouse models of muscular dystrophy [S55‐S57], sarcopenia [S58, S59], and amyotrophic lateral sclerosis (ALS) [S60], but has yet to be investigated in PD. This evidence concerns the gene AGRN and Parkinson disease.