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. The goal of the study is to advance our understanding of the cause of these disorders, the best tools to diagnosis them, and the best way to manage and treat them. Participation may involve collection of biological samples (e.g., blood, saliva, etc.), collection of medical information (e.g., medical records, genetic test results, radiology images, etc.), participation in functional assessments performed by physical and/or occupational therapists, and/or participation in interviews or electronic surveys. Participation may also include research-based genetic testing, or other laboratory tests that look at the presence of molecules, enzymes, etc. thought to be associated with a specific diagnosis.