C4B and systemic lupus erythematosus: The correlation of CNVs in various immune-related genes including IL12B (GeneID 3593)3, TBX21 (GeneID 30009)3, TLR7 (GeneID 51284)4, and CCL3L1 (geneID: 6349)5, in addition to MHC class III genes such as C4A (geneID: 720) and C4B (geneID: 721)6,7 with SLE susceptibility has been reported.