Particularly, C9 plasma protein levels in MS cases were 0.53 HC SD higher (95% CI: 0.25, 0.81) compared to healthy controls, with a slightly higher difference found in SPMS cases compared with healthy controls (i.e., 0.62 HC SD, 95% CI: 0.18, 1.07). Here, C9 is linked to myeloid sarcoma.