C4A and rheumatoid arthritis: For example, C4 CNVs were associated with SLE.[16] In CD, HBD-2 showed fewer copy numbers,[17] and CNVs of FCGR3B were linked to RA[18] and SLE.[19] However, few published papers reported whether copy number variations of genes could affect the predisposition of GD.[4,5,20,21]