Whole exome sequencing with a next generation sequencer is increasingly being used for identifying new genes and for diagnosing genetic disorders. Numerous causative genes have been identified in Mendelian disorders as well as cancers and multifactorial disorders. Among inborn errors of development, recent advances have been noted in the identification of genes for ciliopathy, diseases with aberrant chromatin remodeling and RASopathies. We have studied molecular mechanisms, epidemiological features and mouse modeling for RASopathies, a group of phenotypically overlapping syndromes caused by germline mutations that encode components of the RAS-MAPK pathway. I will present the expanding disease entity in RASopathies/mosaic RASopathies, the mechanism of cancer predisposition, mouse modeling and therapeutic approaches for RASopathies.