Marker gene pool, method for assessing the reparative and / or therapeutic protective effects of ultraviolet radiation of a compound or material, compound or material having ultraviolet protective, repairing or therapeutic effects, methods for improving and / or treating, for reversing and / or repair photo-damaged or photo-aged skin, and to assess whether a substance can repair or reverse the effects of photo-damage or photoaging related to UV radiation exposure, substance or material having photo-repairing or reversing effects or photoaging, composition or formulation, photoprotective or photoprotective or anti-photoaging formulation, methods for assessing skin damage or an ultraviolet-induced skin replacement following exposure to uv radiation, to prevent photoaged or photoavariated skin, to identify or select individuals who are susceptible useful or highly sensitive to skin photoaging or photoaging following exposure to UV radiation, and kit for assessing the photoaging or photoag