In 3 patients with MPGN associated with MC and a history of HCV infection confirmed by the presence of serum anti-HCV antibodies with a negative viral load, no evidence of occult HCV infection was found in PBMCs and in the cryoprecipitate, but HCV-NS3 antigen was present in the kidney biopsy in one of them 14. This evidence concerns the gene KRAS and primary membranoproliferative glomerulonephritis.