We stratified the patients with SLE who were positive for anti-U1-RNP antibodies (FEIA, n = 34) into those with (n = 21) or without (n = 13) concomitant anti-RNP70 antibodies and found no differences regarding clinical characteristics (age, disease duration, ACR criteria, cSLEDAI-2K, SDI and RP) or laboratory variables (blood cell counts, C3 and C4) between the groups. This evidence concerns the gene C4A and systemic lupus erythematosus.