Chromosome 12 annotated sequence completed 16/3/06. By the Baylor College of Medicine Researchers from Baylor College of Medicine's Human Genome Sequencing Center have published the annotated sequence of chromosome 12.

The sequencing and annotation of the chromosome's 132 million nucleotides, reported in the journal Nature, has enabled the researchers to identify more than 1400 genes.

The chromosome also contains one of the longest stretches of DNA that has remained intact through much of evolution. "Going back to the 'out of Africa time' and the different lineages of the human race, this section of the chromosome has been preserved intact," said Dr George Weinstock, co-director of the Human Genome Sequencing Center.

Other chromosomes change as the genetic material from parents mix and form new combinations that are found in their progeny.

The chromosome is of high interest because it is fairly dense in disease-related genes, particularly those involved with cancer. These include ETV6 gene, which is associated with various types of leukemias. It also contains the gene for CD4, the receptor that allows HIV, the virus associated with AIDS, entry into the T-lymphocytes, starting the process of disabling the body's immune system.

Chromosome 12 appears to be the most slowly evolving of all the chromosomes. It was formed from a reciprocal rearrangement of two ancient chromosomes. This means that pieces of each of the ancient chromosomes broke off and joined to the other chromosome. In this case, chromosomes 12 and 22 were formed from these ancestral chromosomes. Lemurs, a distantly related primate, have the ancient chromosome arrangement, while humans and more closely related primates have chromosomes 12 and 22.

The work involved collaboration with the Harvard Medical School-Partners Healthcare Center for Genetics and Genomics and was funded by the National Human Genome Research Institute of the National Institutes of Health.

Adapted from a news release by the Baylor College of Medicine .

Further reading

Scherer SE, et al. The finished DNA sequence of human chromosome 12. Nature. 2006 Mar 16;440(7082):346-51. Abstract