C4A and systemic lupus erythematosus: Such phenomena are in stark contrast to those observed in the genetics of human systemic lupus erythematosus (SLE), in which low GCNs of C4T or homozygous C4A deficiency (C4T=2, OR=6.51; C4A=0, OR=5.27) exerted substantially greater risks than those with C4T=3 (OR=1.32) or heterozygous C4A deficiency (C4A=1, OR=1.61).23 24 46 Parallel analyses of C4 structural variants between cases and controls recruited from each geographic location yielded similar results as presented for the entire IIM cohort, which are analogous to replication studies (online supplemental table S1).