During the past few decades,the investigative technologies of molecular biology-especially sequencing-underwent huge advances,leading to the sequencing of the entire human genome,as well as the identification of several candidate genes and the causative genetic variations that are responsible for monogenic skin diseases.These advances provided a solid basis for subsequent studies elucidating mechanisms of monogenic skin diseases and improving our understanding of common skin diseases.Furthermore,these discoveries also contributed to the development of novel therapeutic modalities for monogenic skin diseases.In this review,we have used the disease spectrum caused by mutations in the CYLD gene-Brooke-Spiegler syndrome,familial cylindromatosis and multiple familial trichoepithelioma type 1-as a model for demonstrating the knowledge explosion for this group of diseases.