Natural History of Pearson Syndrome

All patients with confirmed Pearson Syndrome who satisfy the inclusion/exclusion criteria will be offered enrollment into this study. Patients followed at participating NAMDC clinical sites will be enrolled at those sites. Patients who are not followed at participating NAMDC clinical sites and wish to participate may contact one of the member sites directly or their local doctor may direct them to one of the member sites. Both male and female patients from all racial and ethnic backgrounds who satisfy the inclusion and exclusion criteria will be encouraged to participate. Children and adults will be eligible to be enrolled, but we expect the patient population to be mostly children. Each patient with Pearson Syndrome who enrolls in the NAMDC Clinical Registry will be encouraged to participate in this study. Each patient enrolling in this study will be required to enroll in the NAMDC Clinical Registry either prior to or upon enrolling in this study. Demographic, medical history, biochemical, histological, genetic, and other clinical data from the registry will be incorporated into this study. Every effort will be made to minimize the inconvenience to patients of participating in this study. The study-related activities at each patient visit will be kept to a maximum of one hour, and will, whenever possible, be scheduled to coincide with the patient's regular follow-up with his or her treating physician. This study is observational and has no associated medical procedures.