About half of the human genome is composed of repeated sequences derived from mobile elements, generally without pathogenic effect. These include retrogenes, which derive from mRNAs retrotransposed into the genome and may encode functional proteins. Transposition of mobile elements are important elements involved in the evolution of species. Germline pathogenic variants in RB1 gene confer a high risk of retinoblastoma, the most frequent intraocular tumor in children. Here, we described the first report of a full-length retrogene insertion involved in human monogenic disease, as it leads to a chimeric transcript and a non-functional chimeric protein: the insertion of HPF1 retrogene in RB1 gene resulting in cancer predisposition. (By Jessica Le Gall, https://jmg.bmj.com/content/early/2023/08/04/jmg-2022-109105 )