SNCA and multiple system atrophy: The genetic link between mutations and copy number variations of the SNCA locus and MSA is still controversial, given that common variation in the SNCA gene was first identified as a risk factor for MSA in 2009 (Scholz et al., 2009), but this association was not confirmed in subsequent genome-wide association studies (GWAS) (Chen et al., 2015; Sailer et al., 2016).