Skin, Genetic Defects, and Aging

The document detailed the structure and function of the skin, focusing on genetic defects like lamellar ichthyosis, Vohwinkel syndrome, and epidermolysis bullosa simplex, which result from mutations in structural proteins and lead to conditions such as hyperkeratosis and blistering. It also covered skin aging, distinguishing between intrinsic (genetic) and extrinsic (environmental) factors, with a significant emphasis on photoaging from UV radiation. UVA and UVB radiation caused skin damage through different mechanisms, including the production of reactive oxygen species (ROS), which contributed to oxidative damage and extracellular matrix (ECM) degradation. The degradation of structural proteins like collagens and elastins by matrix metalloproteinases (MMPs) and elastases led to thinner skin and reduced elasticity, with chronic UVB exposure also causing the loss of hyaluronic acid in the dermis.