CKiD is an important research study looking at the health of children, teenagers, and young adults who have kidney problems. This research is being done to identify what factors help kidneys stay healthy, and also to see how kidney problems affect health and well-being. Teenagers and young adults 16-22 years old who have been diagnosed with chronic kidney disease (CKD) may be eligible to join the study. The CKiD study has enrolled approximately 1100 children and teenagers across North America since the study began in 2003. Our goal now is to enroll teenagers and young adults in the study. By doing this we can have a better idea of what happens to kidney function and overall health as someone with childhood chronic kidney disease grows up. This will help provide us with a more complete picture of CKD from childhood through adulthood.

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

The primary goal of this research study is to see if newtypes of magnetic resonance imaging (MRI) can be used to measure liver healthin children with autosomal recessive polycystic kidney disease (ARPKD) comparedto healthy controls.  Both children with ARPKDand healthy children, aged 6 years and above can participate.

The purpose of this study is to identify components of a physical activity intervention that are effective and meaningful to teenagers with chronic kidney disease (CKD).

Participants will be assigned to 1 of the 16 study groups and will be asked to wear a Fitbit. Participants will also be given a step count goal, answer questionnaires, and complete hand grip strength assessments.

Participants may also be asked to have one-on-one meetings with an exercise coach.

All visits may be completed remotely.