Despite reports that showed a mutation and loss of heterozygosity in TSC2 in SEGA, one belief implying that the formation of SEGA is caused only by a mutation of the TSC1 or TSC2 gene has been challenged as being incorrect, mainly because cases of patients with SEGA without clinical symptoms associated with tuberous sclerosis and without TSC1/TSC2 mutations have been described [39,61,77]. The gene discussed is TSC2; the disease is tuberous sclerosis.