Characterization and variability of the CFHR3/CFHR4B region. (A) Separation of CFHR3/CFHR4B isoforms by 2DE. Western blot obtained with the heparin-sepharose eluate from control persons C1 and the αCFHR3/4 antibody preparation. (B) CFHR3 and (C) CFHR4B isoform patterns observed in individual samples (C2, C3) or in the pooled-control sample (P). The pH range used in the IEF step is shown at the top of the gels, and a schematic representation of each pattern is shown at the bottom.