For this study, we are studying the relationship between variations in the genes of the immune system called HLA and how they relate to:

1. The risk of developing nephrotic syndrome
2. The response to treatment of nephrotic syndrome and
3. The risk of recurrence of nephrotic syndrome following kidney transplantation.

Participants will be asked to provide a one time blood sample for DNA testing and information about their health will be collected. 

To be eligible, participants must have:

1. Clinical diagnosis of nephrotic syndrome
2. Biopsy proven diagnosis of FSGS or MCD and,
3. History of living or deceased donor kidney transplantation