The complex history of distal human chromosome 1q

Human chromosome 1 has been claimed to be a conserved ancestral chromosome of eutherian mammals. However, two small regions from distal 1q (with orthology to mouse chromosome 11) appear to have a different history. These two regions are proposed to have been added to the ancestor of human chromosome 1 as a single block that was subsequently disrupted by a paracentric inversion. The translocation and inversion appear to have occurred at some time after the primate lineage diverged from a common ancestor with rodents. Reconstruction of the history of distal human chromosome 1q is complicated by the "reuse" of breakpoints in different mammalian lineages and by coincidental shared synteny between humans and cats.