USP40 and Parkinson disease: In addition, two of the nine inversion loci show evidence of inverted exonic regions in two known genes, DOCK3 and USP40. DOCK3 plays an important role in the engulfment of apoptotic cells and in the migration of cells [30], while USP40 encodes an ubiquitin-specific peptidase 40 that is related to Parkinson disease [31].