Inclusion Criteria :  Nephrotic patient without treatment (excluding corticosteroids) Subgroup: Transplanted INS/FSGS patient, recurring his initial disease after transplantation (vs. non-recurrent INS/FSGS) Patient hospitalized or not (2 procedures for stool collection) Patient consenting to samples or for minors, consenting parent  Exclusion Criteria :  Nephrotic patient with immunosuppressive treatment HIV positive patient Patient refusal to use his biological samples Patient under guardianship / curatorship