Among the downregulated genes in PD (MSA-P > PD), key components included those involved in stress adaptation (HSP90AA1, GABRA6, NTRK3, DDX31), signal transduction (HSP90AA1, NTRK3, BTRC, PITPNM1, PPP2R2B), and ribosomal biogenesis (RPL27, DDX31) (Fig. 4E). Here, PPP2R2B is linked to multiple system atrophy.