My father, 72 yr old, having little blood in the first morning urine, but no pain or burning sensation. He is also having nephrotic syndrome , more than 10 gm protein leakage per day. Glomerullies were not found during kidney biopsy . So no proper identification of the category of Nephrotic syndrome was made. Only interstitial inflamation in kidney were found. Immunofluroscence report shows IgA. What can be the cause?