Inclusion Criteria:  recipient of an allogenic renal allograft, have experienced (whatever ongoing or not) at least a whole year with blood creatinine <1.7 mg/dL and proteinuria </=1g/day or /g creatinine despite the COMPLETE discontinuation of immunosuppressive drugs, alternatively, have experienced (whatever ongoing or not) at least a whole year with stable blood creatinine (max 20% variation) and proteinuria above these criteria despite the COMPLETE discontinuation of immunosuppressive drugs  Exclusion Criteria:  Past medical history of allogeneic bone-marrow transplantation / combined organ transplantation