Genetics of TSC
TSC is caused by a mutation (gene change) in one of two genes: TSC1 and TSC2. Genetic testing for TSC at this time is able to detect mutations in the TSC1 or TSC2 genes in approximately 80% of individuals. For the other 20% of individuals without an identifiable mutation, researchers are studying ways to accurately find mutations in these two known genes and look for additional genes that may be involved.
In general, one third of individuals with TSC inherit the genetic condition from a parent. Two thirds of all cases are sporadic, or occur for the first time in a family.
TSC is inherited as an autosomal dominant genetic condition. This means that a mutation in only one copy of the gene causes the condition. Individuals with TSC have a 50% chance of passing their condition to each of their children.