MDGA1 and multiple system atrophy: Only one CpG site in MDGA1 (cg20053110), found to be significantly hypomethylated in the MSA mixed-subtype replication cohort compared to controls (delta beta = − 12%, p = 3.50 × 10−4), overlaps with a 260-bp region (4 CpG sites) significantly hypomethylated in the discovery cohort.