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.

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

Kidney stones are one of the fastest growing health conditions among children, adolescents, and young adults. The rapid increase over a short period of time has resulted in a large number of pediatric patients who require surgery to remove kidney stones with very little information available to guide selection of treatment options. There are three alternative approaches to remove kidney stones:

• Ureteroscopy (an endoscopic outpatient procedure)
• Shockwave lithotripsy (a noninvasive outpatient procedure)
• Percutaneous nephrolithotomy (a minimally invasive surgery with a short hospital stay)

The purpose of this study is to determine how what you eat and drink (your diet), antibiotics you take, and the bacteria that live in your gut (microbiome) contribute to developing kidney stones. Kidney stone disease, known as nephrolithiasis, is also influenced by products of metabolism (metabolites) that are found in your urine. These factors will be examined in participants at least 4 years of age. Each participant will complete three 24-hour dietary recalls and will provide one stool sample and up to two urine samples. The information from this study will help doctors find new metabolic pathways that can be used for treatment of kidney stones.