Her brave boy. Jana Kramer’s 4-year-old son Jace is recovering after undergoing surgery to have a nevus sebaceous birthmark removed. The One Tree Hill alum, 39, shared a photo of her son’s head before ...

Mosaic epidermal nevus syndromes arise from postzygotic mutations that generate lines or patches of affected skin and often involve extracutaneous organs. Activating variants in genes encoding ...