DICER1 and Parkinson disease: Kim et al. (2007) showed that mice lacking Dicer in specific dopamine neurons develop a progressive loss of neurons later in life, displaying a Parkinson’s-like disease. Thus, miRNAs are essential for maintaining dopaminergic neurons in the brain, and participate in the pathogenesis of PD. Furthermore, a recent review has shown that one–fourth (49 out of 202, MIRECORDS database) of “validated” targets of miR-124 are de-regulated in PD (Sonntag, 2010), indicating an important role for miR-124 in the regulation of this disease.