The investigators propose a retrospective exploratory descriptive study to (a) identify and describe experiences that young adults found to enable or hinder their transition and (b) explore these patients ideas for enhancing the transition process. A semi-structured questionnaire administered by phone or face to face to approximately 40 young adults with chronic granulomatous disease (CGD) will gather qualitative and quantitative information about the use of inpatient and outpatient services at the NIH Clinical Center prior to and since the subjects 18th birthdays. Data will be used to develop a program to help NIAID pediatric patients with CGD transition successfully to adult care.