Ultraconserved Elements in the Human Genome

TLDR

These ultraconserved elements, numbering over 5,000 sequences longer than 100 bp, are more highly conserved than proteins and may be essential for mammalian development, although their functions and evolutionary origins remain unknown. The study identified 481 ultraconserved elements longer than 200 bp that are 100 % identical across human, rat, and mouse, also highly conserved in chicken, dog, and fish, and are predominantly located in exons of RNA‑processing genes or near transcription‑regulation and developmental genes.

Abstract

There are 481 segments longer than 200 base pairs (bp) that are absolutely conserved (100% identity with no insertions or deletions) between orthologous regions of the human, rat, and mouse genomes. Nearly all of these segments are also conserved in the chicken and dog genomes, with an average of 95 and 99% identity, respectively. Many are also significantly conserved in fish. These ultraconserved elements of the human genome are most often located either overlapping exons in genes involved in RNA processing or in introns or nearby genes involved in the regulation of transcription and development. Along with more than 5000 sequences of over 100 bp that are absolutely conserved among the three sequenced mammals, these represent a class of genetic elements whose functions and evolutionary origins are yet to be determined, but which are more highly conserved between these species than are proteins and appear to be essential for the ontogeny of mammals and other vertebrates.