The present invention relates to methods for predicting, diagnosing and monitoringskin states and skin diseases. The methods combine the use of non-invasive skincollecting techniques with one or more assays for determining mitochondrialDNA (mtDNA) aberrations and Melanocortin 1 Receptor (MC1R) variants, therebyproviding a comprehensive tool for identifying, predicting and/or monitoringphotoageing, ultraviolet radiation (UVR) damage or skin disease. The methodsof the invention may also be effective in screening for new therapeutic agents,skin care products and treatment regimes, and may also be useful for monitoringthe response of a subject to a preventative or therapeutic treatment.
