C4B and systemic lupus erythematosus: The mrcPCR assay was performed on control and SLE samples to determine the CNs of TNFAIP3, TNIP1, IL12B, TBX21, TLR7, C4A, C4B, CCL3L1, and CCL3L3. To optimize the assays, the relative primer concentrations and competitors were empirically determined, and the final mrcPCR assay information is shown in Supplementary Tables S1–S3.