Retrotransposons, known as “jumping genes,” move from one location to another across the human genome in a “copy-and-paste” manner and sometimes cause genetic diseases. We used long-read genome sequencing to show that an evolutionarily old SVA_D retrotransposon inserted deep in the intron of ATP7A caused occipital horn syndrome, a rare hereditary copper deficiency. A pedigree analysis indicated this retrotransposon had jumped to the site in ATP7A two generations before. The fact that the evolutionarily old retrotransposon moves still actively and increases its copy numbers may have a notable impact on rare genetic disease research. (By Dr. Takeshi Yoshida, https://jmg.bmj.com/content/early/2024/07/02/jmg-2024-110056 )