Endophenotype and Biomarker

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by a complex pathogenesis and very wide clinical phenotypes. To date, a large variety of clinical phenotypes have been grouped into a single diagnosis, and a single therapeutic approach has been used for AD patients with different clinical phenotypes without considering heterogeneity. As a result, there is no precise preventive or therapeutic approach, and there is an increasing demand for the classification of new phenotypes that reflect the heterogeneity of AD. Accordingly, many attempts have been made to classify complex clinical phenotypes into more uniform phenotypes by defining new biomarkers. As we are entering the era of personalized medicine and advanced biological techniques are being developed, the establishment of endophenotypes through a systemic biological approach is considered as a breakthrough in the present situation. This chapter reviews the classification of the classic clinical phenotypes of AD and examines why biomarkers and endophenotypic concepts are needed in the era of personalized medicine, and the current biomarker candidates. Although there is no biomarker available in the clinical field yet, various biomarkers discussed in this chapter will present a new paradigm of AD treatment, prevention, and prediction of prognosis in the near future.