Their results showed a significant decrease for C9 plasma levels in both RRMS, SPMS cases, and overall MS cases, but at the same time significantly increased plasma levels of all the other complement proteins analyzed, i.e., C3 (where a difference between MS cases and healthy controls did not result significantly in our sample), C4, C4a, C1 inhibitor, and factor H were highlighted. Here, C4A is linked to myeloid sarcoma.