They found that highest urinary complement activation products (CAPs) excretion, namely C5a, C5b-9, and factor Bb, was found in proliferative and proliferative + membranous nephropathy as compared to lupus nephritis class I, II or V among 149 SLE patients undergoing kidney biopsy for suspected lupus nephritis. This evidence concerns the gene C5AR1 and lupus nephritis.