TSC1: The tuberous sclerosis 1 gene. The product of the TSC1 gene is a protein called hamartin. This protein interacts with tuberin, the product of the TSC2 gene. These two proteins form a complex and play a role in cell growth and division. TSC1 functions as a tumor suppressor gene.
Mutation in the TSC1 gene causes tuberous sclerosis. The mutant TSC1 gene produces an abnormal version of hamartin. This abnormal protein cannot form a complex with tuberin, the product of the TSC2 gene. Loss of this protein complex causes cells to divide too often, resulting in cell overgrowth and benign tumors. The TSC1 gene is located on the long (q) arm of chromosome 9 in band 9q34.