Picture an orchestra where, with age, the conductor keeps skipping individual musicians. Something similar happens in blood cells: when a cell divides, a chromosome can fail to make it into the new cell. This used to look like pure chance. But when scientists compared the DNA of hundreds of thousands of people, a pattern emerged: everyone has their own chromosomes that go missing more often. Think of inherited notes that keep dropping out of the score.
Each chromosome turned out to have its own genetic variants. The X chromosome has 245 of them, the Y chromosome 828. Ten other chromosomes yielded another 173 regions. It turns out these losses barely affect health: there is only a weak link to prostate cancer. The conductor slips up, but the music plays on.
One of the structural variants discovered, a hybrid chromosome 13/22, arose from a rare recombination between centromeres and occurs in roughly one in 30 people of southern European ancestry.
Not published on arXiv. Here are its page, the PDF and the formalization: you can check it yourself, not only read our account.