Most studies that implemented (NI-)ONDC patients as control group concluded there was no difference with the blood levels of the investigated complement factor (i.e., C3a, C4, C4a, C5, C5a, C9, fH, factor Ba) compared to (NI-)ONDC patients (96, 99, 103, 113), except one study which reported decreased C3 levels in serum of MS patients versus control patients with low back pain (96). Here, C4A is linked to myeloid sarcoma.