C3 and focal segmental glomerulosclerosis: According to the correlation coefficients between IgM and C3 deposition with other clinical and histological variables in primary and secondary FSGS, there were significant positive correlations between the IgM and C3 deposition and between IgM and mesangial deposits on EM in the secondary FSGS group, indicating that IgM deposition is associated with C3 deposition and EM mesangial deposits only in the secondary FSGS group (Table 4).