DESCRIPTION: The goal of this proposal are to systematically study a cohort of neuroglycopenia patients to determine if there is a phenotypic correlation with specific defects in the GLUT-1 gene, a glucose transported that has been found to have point or nonsense mutations in 5 or 17 patients so far. In addition, GLUT-1 karyotypic rearrangements have found in two patients. These findings indicate that mutations which result in a loss of GLUT-1 activity are linked to the onset of the phenotype. The first Aim will be carry out genotypic analysis on the existing patients and on new patients as they become available at a rate of approximately 4/year. The focus of Aim 2 will be an extensive characterization of the phenotype of existing and new patients. Aim 3 will be to develop GLUT-1 deficient mice by homologous recombination and to carry out a neuropathological analysis of these animals.