TSC1 and tuberous sclerosis: The TSC1 gene is located on chromosome 9q34 and consists of 23 exons that encode the hamartin (Slegtenhorst et al., 1997) and the TSC2 gene is located on chromosome 16p13 and consists of 42 exons that encode the tuberin (European Chromosome 16 Tuberous Sclerosis Consortium,, 1993).