The Nosology and Etiology of Leukodystrophies of Unknown Causes

Genetic white matter disorders (leukodystrophies) are estimated to have an incidence of 1:5000 live births. As many as 50% of patients with white matter disease remain undiagnosed after conventional neuroimaging, biochemical and genetic testing, and therefore have unclassified leukodystrophies. Moreover, the mechanisms of disease in many leukodystrophies of known cause are very poorly understood: many are systemic abnormalities that manifest only in white matter. The purpose of this study is to: (a) define novel homogeneous groups of patients with leukodystrophy and work toward finding the cause of these disorders and (b) establish disease mechanisms in selected classified leukodystrophies. In order to achieve these goals, patients with leukodystrophy will be analyzed by clinical, neurophysiological, biochemical and genetic means. For goal (a), patients would have been diagnosed as having an unclassified leukodystrophy or no known cause of their leukodystrophy at outside centers. At the Clinical Center, such patients will undergo a series of neuropsychological, blood, urine, spinal fluid, radiological, and peripheral tissue pathological tests. Some of these tests will be part of a standard battery while others will be tailored to individual patients. For goal (b), selected leukodystrophies with a defined genetic cause will be selected for further mechanistic study, using clinical and laboratory tools to establish increased understanding of the underlying pathophysiology. It is hoped that the present study will help clarify the nosology of the leukodystrophies and significantly advance our understanding of the pathogenesis of these diseases.