The purpose of this research study is to collect different types of samples (such as stool, swabs, urine) to form a biorepository.

The Children Brain Tumor Tissue Consortium (CBTTC) is a collaborative multi-institutional cooperative research program dedicated to the study of childhood brain tumors.

Healthy control children are needed to help participate in a study on Immunometabolic Dysregulation.

Collect data and blood samples to make observations and determinations about rate and severity of graft-versus-host disease in HCT patients.

CHOP is conducting a research study that will help make it possible to do future studies in children and family members both with and without problems with their brain and nervous system.

This study involves the collection of medical information and samples from people with a confirmed or suspected leukodystrophy or related disorder affecting the white matter of the brain, as well as "healthy controls" who are not known to be affected by one of these disorders.