BDNF and Parkinson disease: They found that miR-193b was overexpressed in peripheral blood mononuclear cells of PD patients, leading to sustained downregulation of PGC1α, Fibronectin type III domain-containing protein 5 (FNDC5), brain-derived neurotrophic factor (BDNF), and TFAM, exacerbating mitochondrial dysfunction and neuronal degeneration.