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Tuberous Sclerosis Complex

Main Features

  • Benign tumors of the brain, kidney, lung, heart and eyes.
  • A phakomatosis

Eye Findings

  • Retinal astrocytic hamartomas 34-75% of patients with TSC.
    • flat, translucent lesions, multinodular “mulberry” lesions, and transitional types.
    • usually non-progressive but can occasionally show subretinal fluid and progression.
    • Typically located along the arcades, adjacent to the optic nerve, or in the retinal periphery.
  • Retinal achromic patches 34%
    • hypopigmented areas similar to the hypomelanotic macules seen on the skin
    • Usually non-progressive and do not significantly affect vision
  • Refractive errors (myopia, hyperopia, and astigmatism),
  • Strabismus
  • Angiofibromas of the eyelids- rare
  • Coloboma- rare

Other Findings

  • Angiofibromatosis
  • Seizures
  • Developmental delay

Etiology

  • Autosomal Dominant with near complete penetrance but variable expressivity due to Knudson's two-hit hypothesis
  • Mutations result in unregulated cell growth leading to hamartomas
  • Mutations in TSC1 (25%)
    • Encodes for gene hamartin- a tumor supressor gene
    • Chromosome 9q34
  • Mutations in TSC2 (75%)
    • Encodes for gene tuberin- a tumor supressor gene
  • Both genes inhibit the mammalian large of rapamycin (mTOR) pathway

Resources

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