Moreover, there was no significant difference in the Gd-IgA1 levels of patients with other renal diseases compared with healthy controls, suggesting that a highly elevated Gd-IgA1 level is specific to IgA nephropathy and could be used to distinguish IgAN from membrane nephropathy, MCD, Alport syndrome or other renal diseases. This evidence concerns the gene IGHA1 and IgA glomerulonephritis.