Another Piece in the Puzzle

Scientists have unravelled the complete genetic instructions of a third human chromosome. It contains a huge amount of information about diseases ranging from obesity and eczema to dementia.

Chromosome 20 is the first chromosome to be deciphered since scientists from Britain, China, France, Germany, Japan and the United States sequenced all the estimated 40,000 or more genes in humans earlier this year.

Chromosome 20 is one of the 24 bundles of DNA that carry our genetic material. It is the largest human chromosome to be finished so far. The work published on Wednesday is part of the ongoing Human Genome Project, an international effort to read the genetic make-up of humans.

"This is one more completed chapter of our genomic anatomy textbook - medical research will be using this information for decades to come in its quest to tackle our common diseases," said Dr Mike Dexter, the director of the Wellcome Trust, the world's largest medical charity.

Scientists from The Wellcome Trust Sanger Institute in Cambridge, England, led by Dr Panos Deloukas, completed the sequence which is reported in the science journal Nature.

"It is a unique piece of the puzzle," Deloukas said. "We have probably annotated more than 95 percent of this chromosome."

The discovery is another important step in understanding the link between genes and diseases. And what makes individual human beings unique. Any two humans are 99.9 percent similar. The 0.1 percent difference in DNA is what makes an individual unique.