The most important finding in these studies is the significant association between the low levels of sCD89-IgA complex in sera of IgA nephropathy patients and the progression of severe IgA nephropathy. One of our studies is the first investigation of the importance of IRF5, STAT4 and TRAF1-C5 gene polymorphisms in patients with IgA nephropathy and showed no evidence of an association of these genes with the development of IgA nephropathy or Lupus nephritis. The results did not suggest any overlap of genetic risk factors in the two diseases, even demonstrated a contrast between IgA nephropathy and Lupus nephritis.