A better understanding of metabolic disorders which affect the nervous system is the goal of this project. In some phases, the studies are purely diagnostic and are applied to assist in diagnosing the less common disorders of metabolism. Other phases deal with biochemical observations in known disorders that suggest steps in the pathogenesis of the disease. In some poorly understood groups of neurologic disease, studies are conducted to draw biochemical correlations where none had previously been known or were poorly developed. Therapeutic trials are conducted in selected disorders.