Tuberous sclerosis complex: disease modifiers and treatments

Tuberous sclerosis complex (TSC) is an autosomal dominant neurocutaneous disorder involving benign growths in multiple organ systems of affected patients. Variable phenotypes from mild to severe have been reported for related as well as unrelated patients affected by TSC. The two causative genes, TSC1 and TSC2, which code for hamartin and tuberin respectively, play central roles in regulating cell survival and proliferation signaling pathways. The severity of disease phenotypes of TSC patients is influenced by the activities of genes both up and down-stream in the associated pathways.

The high-expressing12CA repeat variant of the IFNG gene was suggested to contribute lower risk for kidney angiomyolipomas in patients with TSC2 gene mutations. Genetic modifiers for TSC have been localized on chromosomes 3 and 5 of the rat genome. We performed association studies linking the c.68C allele of the 5-hydroxytryptamine receptor 2C gene to lower seizure risk in TSC-affected individuals.

Genetic and epigenetic factors affecting the activity of each and every interacting partner of the tuberin-hamartin complex could potentially alter the disease presentation. Identifying functional polymorphic variants of interacting partners affecting TSC gene functions will delineate the mechanisms leading to TSC disease severity, ultimately resulting in treatment strategies.