Given the known role of the IgA system in the pathogenesis of IgA nephropathy, a kidney disease caused by glomerular deposition of IgA in the setting of pharyngitis and other mucosal infections, we specifically tested for shared genetic architecture between IgA levels, IgA nephropathy, and tonsillectomy61 by systematic lookups and co-localization analyses of genome-wide significant loci. This evidence concerns the gene CD79A and IgA glomerulonephritis.