Loss-of-function mutations or DA neuron-specific inactivation of the respective Drosophila homologues of PINK1 [161, 170-173], Parkin [61, 174-176], DJ-1 [69, 177-182], LRRK2 [165, 166, 173, 183], and HtrA2 [184-186] can also lead to parkinsonism-like DA cell loss and locomotor defects. This evidence concerns the gene LRRK2 and Parkinson disease.