The retrogenome represents a fascinating frontier in genetic research, encompassing the collection of retroelements that have been integrated into the genome through the retro life cycle, where DNA is transcribed into RNA and then reverse-transcribed back into DNA. This cycle enables the "copy and paste" in the genome, thus innovating and reorganizing its structure. Key components of the retrogenome include LINE-1 (Long INterspersed Element-1), the most abundant type of retroelement in the genome, endogenous retroviruses (ERVs), retroviral sequences acquired by host genomes through germline infections of their exogenous counterparts, and retrocopied genes, which are genes duplicated by LINE-1s and/or ERVs.

As innovators and reorganizers of the genome, the study of retroelements raises several intriguing questions: How do retroelements like LINE-1s, ERVs, and retrogenes contribute to genome innovation while maintaining genomic stability? What functions do retroelements serve for the genome? How does their activity shape the evolution of the host genome? How do retroelements vary among different host populations? Understanding the retrogenome provides valuable insights into the mechanisms of genomic evolution and the potential implications for human health and disease, making it a critical area of study in both basic and applied biomedical research.