Book excerpt: This Research Topic addresses the human diseases caused by a malfunction of the RNA metabolism. We aim at strengthening the link between fundamental research and therapeutic applications. In eukaryotes, RNA is transcribed from genomic DNA. RNA molecules undergo multiple post-transcriptional processes such as splicing, editing, modification, translation, and degradation. A defect, mis-regulation, or malfunction of these processes often results in diseases in humans, referred to as 'RNA diseases'. There is an increasing number of studies focused on RNA diseases, which are aimed at uncovering the fundamental molecular mechanisms at play in order to develop therapeutic approaches.