With regards to complement regulatory proteins, the genetics of the factor H (FH) and FH-related (FHR) family have been studied in patients with SLE, with the finding that the FH locus is linked to SLE risk (Zhao et al., 2011) and also that the relatively common linked deletion of FHR3 and FHR1 genes contributes an elevated risk to the development of SLE across multiple ethnic populations (Zhao et al., 2011). This evidence concerns the gene FH and systemic lupus erythematosus.