Overview
- The Nature Communications paper, released Tuesday, reports that all pups in the 58th generation died after birth following a 20‑year effort that produced more than 1,200 mouse clones.
- Whole‑genome sequencing found cloned lines carried roughly triple the mutations seen in naturally bred mice, including large structural changes and missing chromosomes.
- Researchers observed the downturn around the 25th to 27th generations as fertility waned and placentas enlarged, signaling the build‑up of harmful variants.
- When late‑generation clones mated with male mice, their young were healthier with fewer mutations, supporting the idea that sex shuffles DNA to purge damage.
- The team sees no fix with current nuclear‑transfer cloning and suggests banking original donor cells or developing better methods, a caution for conservation and livestock plans that bank on endless re‑cloning.