For example, a low measured CH50, reciprocal for 50% hemolysis, low levels of C3 and C4, and a normal factor B value, are indicative for classical pathway activation implicated in autoimmune disorders like Sjogren’s syndrome, systemic lupus erythematosis (SLE), or rheumatoid arthritis [85]. This evidence concerns the gene C4A and systemic lupus erythematosus.