COQ2 and multiple system atrophy: Loss of function mutation in the coenzyme Q2 (COQ2) gene encoding the COQ10-synthesizing enzyme in Japanese familial and sporadic cases and discordant loss of copy numbers of (src homology 2 domain containing)-transforming protein 2 (SHC2) in monozygotic twins and Japanese patients with sporadic MSA have been reported predominantly for MSA-C; however, this was not confirmed in other populations [23–25].