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We report the recent diagnostic criteria for TSC and provide an overview of the molecular genetics, molecular pathophysiology, and neuropathology of TSC. Important diagnostic criteria for TSC include facial angiofibromas, ungual fibromas, retinal hamartomas, and cortical tubers. Both familial and sporadic TSC cases occur. Approximately 50% of TSC families show genetic linkage to TSC1 and 50% to TSC2. Among sporadic TSC cases, mutations in TSC2 are more frequent and often accompanied by more severe neurologic deficits. Multiple mutational subtypes have been identified in the TSC1 and TSC2 genes. The TSC1 (chromosome 9) and TSC2 (chromosome 16) genes encode distinct proteins, hamartin and tuberin, respectively, which are widely expresse d in the brain and may interact as part of a cascade pathway that modulates cellular differentiation, tumor suppression, and intracellular signaling. Tuberin has a GTPase activating protein-related domain that may contribute to a role in cell cycle passa ge and intracellular vesicular trafficking. Identification of tuberous sclerosis complex (TSC) gene mutations has fostered understanding of how brain lesions in TSC are formed. Further characterization of the roles of hamartin and tuberin will provide p otential therapeutic avenues to treat seizures, mental retardation, and tumor growth in TSC. |
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