Nephrotic Syndrome Study Network

Cohort A (biopsy cohort) Inclusion Criteria: Patients presenting with an incipient clinical diagnosis for FSGS/MCD or MN or pediatric participants not previously biopsied, with a clinical diagnosis for FSGS/MCD or MN meeting the following inclusion criteria: * Documented urinary protein excretion ≥1500 mg/24 hours or spot protein: creatinine ratio equivalent at the time of diagnosis or within 3 months of the screening/eligibility visit. * Scheduled renal biopsy Cohort B (non-biopsy, cNEPTUNE) Inclusion Criteria: * Age \<19 years of age * Initial presentation with \<30 days immunosuppression therapy * Proteinuria/nephrotic * UA\>2+ and edema OR * UA\>2+ and serum albumin \<3 OR * UPC \> 2g/g and serum albumin \<3 Exclusion Criteria (Cohort A\&B): * Prior solid organ transplant * A clinical diagnosis of glomerulopathy without diagnostic renal biopsy * Clinical, serological or histological evidence of systemic lupus erythematosus (SLE) as defined by the ARA criteria. Patients with membranous in combination with SLE will be excluded because this entity is well defined within the International Society of Nephrology/Renal Pathology Society categories of lupus nephritis, and frequently overlaps with other classification categories of SLE nephritis (68) * Clinical or histological evidence of other renal diseases (Alport, Nail Patella, Diabetic Nephropathy, IgA-nephritis, monoclonal gammopathy (multiple myelomas), genito-urinary malformations with vesico-urethral reflux or renal dysplasia) * Known systemic disease diagnosis at time of enrollment with a life expectancy less than 6 months * Unwillingness or inability to give a comprehensive informed consent * Unwillingness to comply with study procedures and visit schedule * Institutionalized individuals (e.g., prisoners)