In May 2000, Human Genome Project scientists led by German and Japanese teams described the finished genome sequence of human chromosome 21, the second human chromosome to be fully sequenced. An extra copy of chromosome 21 causes Down syndrome and genes on the chromosome have been linked to diseases like Alzheimer's and certain forms of cancer.
The published sequence contained approximately 33,500,000 base pairs. Chromosome 21 appears to have less than 300 genes.
Hattori, M., Fujiyama, A., Taylor, T.D., Watanabe, H., Yada, T., Park, H-S., Toyoda, A., et al. The DNA sequence of human chromosome 21. Nature, 405: 311-319. 2000. [Full Text]
Last Reviewed: July 26, 2013