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Sun exposure causes somatic second-hit mutations and angiofibroma development in tuberous sclerosis complex

Magdalena E Tyburczy1, Ji-An Wang, Shaowei Li

  • 1Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.

Human Molecular Genetics
|November 26, 2013
PubMed

Insights

Tuberous sclerosis complex (TSC) facial angiofibromas may result from UV-induced DNA damage. Limiting sun exposure could reduce tumor development in individuals with TSC.

Area of Science:

  • Genetics
  • Dermatology
  • Oncology

Background:

  • Tuberous sclerosis complex (TSC) involves tumor formation due to mutations in TSC1 or TSC2 tumor suppressor genes.
  • The mechanism of somatic second-hit mutations in TSC tumors remains unclear.
  • Understanding these mutations is crucial for managing TSC-related growths.

Purpose of the Study:

  • To investigate the genetic basis of somatic second-hit events in TSC skin tumors.
  • To identify the specific mutations and their origins in TSC-associated lesions.
  • To explore the potential role of environmental factors in TSC tumor development.

Main Methods:

  • Fibroblast-like cells were cultured from 29 TSC skin tumors across 22 subjects.
  • Next-generation sequencing was employed to detect germline and second-hit mutations in TSC1/TSC2.
  • Analysis included assessment of mosaicism and mutation patterns in relation to tumor location.

Main Results:

  • Mutations in TSC1/TSC2 were identified in 82% of subjects.
  • Mosaicism for mutations was present in 44% of affected subjects.
  • UV-signature mutations (CC>TT) were found in 50% of somatic point mutations, exclusively in facial angiofibromas from sun-exposed areas, suggesting independent tumor origins.

Conclusions:

  • UV-induced DNA damage is implicated as a cause of second-hit mutations in TSC facial angiofibromas.
  • These findings suggest that sun protection measures may help reduce the incidence and severity of TSC facial lesions.
  • Targeting UV exposure could be a preventative strategy for specific TSC manifestations.

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