A Study to Understand the Genetics and Clinical Course of Focal Segmental Glomerulosclerosis (FSGS), Treatment-Resistant Minimal Change Disease (TR-MCD), and Diabetic Nephropathy (DN)

Inclusion Criteria: For FSGS/TR-MCD patients : 1. Competent and willing to provide informed consent and adhere to all study assessments and restrictions. 2. Male or female ≥ 18 years of age with FSGS or TR-MCD at the time of providing written informed consent. 3. Diagnosis of FSGS or TR-MCD, based on either biopsy or genetic testing. 4. Urinary protein to creatinine ratio (UPCR) ≥ 1.0 g/g. 5. Estimated glomerular filtration rate (eGFR) ≥ 45 mL/min/1.73 m2. For DN patients: 1. Competent and willing to provide informed consent and adhere to all study assessments and restrictions. 2. Male or female ≥ 18 years of age with DN at the time of providing written informed consent. 3. Diagnosis of type 2 diabetes 4. Urinary albumin to creatinine ratio (UACR) ≥ 150 mg/g. 5. Estimated glomerular filtration rate (eGFR) ≥ 45 mL/min/1.73 m2. Exclusion Criteria: For FSGS/TR-MCD patients: 1. Evidence of another kidney disease or kidney disease secondary to an infectious process. 2. History of human immunodeficiency virus (HIV), hepatitis B, or hepatitis C. Patients whose results are compatible with prior immunization or treatment may be included. 3. Body mass index (BMI) \> 42 kg/m2. 4. Significant history or evidence of clinically significant disorder, condition, current illness, or disease that, in the opinion of the Investigator, would pose a risk to patient safety or interfere with the study evaluation, procedures, or completion (eg, severe cardiac disease, cardiac conduction defect, or severe or chronic hepatobiliary disease). 5. History of malignancy not in remission within the last 5 years other than adequately treated basal cell or squamous cell skin cancer or cervical carcinoma in situ. 6. History of any organ or bone marrow transplant, including kidney grafts. 7. History of alcoholism or drug/chemical abuse within 12 months. 8. Preplanned surgery or procedures that would interfere with the conduct of the study. For DN patients: 1. Evidence of another kidney disease or kidney disease secondary to an infectious process. 2. History of HIV, hepatitis B, or hepatitis C. Patients whose results are compatible with prior immunization or treatment may be included. 3. BMI \> 42 kg/m2. 4. Significant history or evidence of clinically significant disorder, condition, current illness, or disease that, in the opinion of the Investigator, would pose a risk to patient safety or interfere with the study evaluation, procedures, or completion (eg, severe cardiac disease, cardiac conduction defect, or severe or chronic hepatobiliary disease). 5. History of malignancy not in remission within the last 5 years other than adequately treated basal cell or squamous cell skin cancer or cervical carcinoma in situ. 6. History of any organ or bone marrow transplant, including kidney grafts. 7. History of alcoholism or drug/chemical abuse within 12 months. 8. Preplanned surgery or procedures that would interfere with the conduct of the study. 9. Renal disease that requires immunosuppressive therapy (currently, or in the past).