The human genome has a glitch. It is filled with restless bits of ‘jumping’ genes that, in their movement, scramble the genome from the inside out. Their mobility causes chaos, disrupts genes and can spark the early development of cancer.
In a new review article published in Science, Mater Research’s Dr Nathan Smits and Dr Sandra Richardson explore how recent breakthroughs in long-read DNA sequencing have finally exposed the massive genomic wreckage caused by LINE-1 (L1) mobile elements.
L1 moves through a ‘copy-and-paste’ mechanism, disrupting the genome by inserting a new copy of itself. The research team argue that L1 doesn't always insert itself cleanly and that the copy-and-paste process itself can misfire and cause large-scale rearrangements in our DNA.
While scientists have known for decades that the human genome contains around 500,000 copies of L1, most are inactive molecular fossils. Until recently, the extent to which active L1 elements contribute to human disease, including cancer, has remained a puzzle, hidden by the limitations of older short-read DNA sequencing that could only see tiny fragments of this process.
Dr Smits said that when this copy-and-paste mechanism triggers in two different locations at the exact same time, it can fuse two completely different chromosomes together.
“Merging these sections of code together can crash the biological program, potentially helping to drive the out-of-control multiplication of cells that leads to cancer,” Dr Smits said.
"For years, trying to figure out where these genes were jumping using older DNA sequencing technologies was like trying to debug a computer program line by line. New long-read sequencing lets us see the whole pipeline, showing us exactly where and how this rogue copy-and-paste mechanism tears apart the genome and drives cancer."
Dr Richardson said that it’s the difference between trying to read a book that had been put through a paper shredder versus finally getting the whole pages.
"We can now see exactly where these jumping genes come from and the massive structural damage they cause when they land."
The review also poses compelling questions for future research, noting that since L1 is highly active in human embryos and brain cells, these massive genomic rearrangements may be happening outside of cancer as well.
The full article, titled “Untangling the LINEs” was published in Science in April 2026.
