Ravanidis et al. performed qRT-PCR of total RNA in patients with PD and healthy controls and found that Hsa_circ_0000497 was downregulated in the peripheral blood of patients with PD, which is encoded by the SLAIN motif family member-1 (SLAIN1) gene, microtubule-associated proteins, and is essential for axon elongation in neuronal development. The gene discussed is SLAIN1; the disease is Parkinson disease.