Nephrotic Syndrome Study Network is a research project aimed at better understanding rare kidney diseases, such as Minimal Change Disease (MCD), Focal Segmental Glomerulosclerosis (FSGS), and Membranous Nephropathy (MN). These conditions can lead to serious kidney failure called End-Stage Renal Disease (ESRD), which requires costly treatments. The current treatments for these diseases often have bad side effects and don't always work well because they don't target the root causes. This study is working with top medical groups to find out more about these diseases and improve treatments. Participants will help by providing health information and samples for research.

• Participants may be asked to provide a urine sample or undergo a kidney biopsy (a small piece of kidney tissue is examined).
• Participants must meet certain health criteria, like specific protein levels in their urine, to join the study.
• People who have had a kidney transplant or certain other diseases can't participate.