The remaining, non-precipitated RA sample pool supernatant and the HD sample pool (with added heat-treated IgG) were analysed by gelfiltration chromatography (S3 Fig), which showed that IgM, IgA and IgG eluted sequentially in both samples, but that elution profiles of the Igs were broader for the RA sample pool. This evidence concerns the gene CD79A and rheumatoid arthritis.