Chromosomal rearrangements in the human and chimpanzee lineages

Among the structural differences evident between humans and chimpanzees are large chromosomal rearrangements which are visible by cytogenetic analysis. These include the fusion that created human chromosome 2, nine pericentric inversions and numerous chromatin additions at the telomeres. Recently performed genome-wide comparative analyses have also revealed a considerable number of submicroscopic structural variations which contribute significantly to the chromosomal divergence between humans and chimpanzees. This microheterogeneity comprises inversions, duplications and deletions ranging in size from a few base pairs up to several megabases. These copy number differences appear to have given rise to several hundred megabases of genomic deoxyribonucleic acid (DNA) sequence that are either present or absent in humans as compared to chimpanzees. Since many of these lineage-specific copy number differences contain genes, humans and chimpanzees may differ significantly with respect to their gene content, and some of these differences could have influenced the evolution of lineage-specific traits