C9orf72 and Parkinson disease: Myr‐C9orf72 transmembrane peptide attenuates abnormal autophagy, such as the downregulation of LC3II/I expression, upregulation of p62 and α‐synuclein expression, and dopaminergic neuron death and dyskinesia in PD by interfering with Cdk5 phosphorylation of the Ser9 site of C9orf72 protein.