However, the biopsy also exhibited mild increase in mesangial matrix and minimal segmental increase in cellularity on light microscopy, and there was mild mesangial staining for IgA, with trace amounts of C3, κ and λ light chains on immunofluorescence microscopy, raising the possibility of a concomitant mild IgA nephropathy. The gene discussed is CD79A; the disease is IgA glomerulonephritis.