that included 100 IgA nephropathy patients with varying proportions of glomerular crescent formation demonstrated that urinary levels of C3a and C5a (representing the common pathway), C4d and MBL (representing MBL pathway), and C5b-9 (representing terminal pathway) were positively correlated with the proportion of glomerular crescents on renal biopsy, serum creatinine levels, and proteinuria. The gene discussed is MBL2; the disease is IgA glomerulonephritis.