With the advance of molecular techniques,TSC1andTSC2were cloned in the 1990s, and genotype-phenotype correlations were made possible.1Tuberous sclerosis complex is caused by mutations inTSC15at 9q34, which produces hamartin,6and mutations in TSC2 at 16p13,7which produces tuberin.8Both proteins act as tumor suppressors.9 The gene discussed is TSC2; the disease is neoplasm.