Scientists have sequenced the last remaining chromosome in the human genome.

Known as "chromosome 1," it contains 3,141 genes—nearly twice as many as the average human chromosome—and makes up eight percent of the human genetic code.

"This achievement effectively closes the book on an important volume of the Human Genome Project," Dr. Simon Gregory, head of the sequencing project at the Sanger Institute in England, told Reuters.

The project began in 1990 to identify the genes and DNA sequences that provide a blueprint for human beings. The sequencing of chromosome 1, which was published online in Nature, took 10 years and 150 British and American scientists.

Chromosome 1 is linked to 350 illnesses, and it is hoped that scientists worldwide, including those in Arizona, will be able to use the data to improve medical diagnostics and treatment.

"Chromosome 1 is the largest, and many of its 3,100 genes have been linked to a number of today's leading illnesses—and no doubt there are more discoveries ahead," said Dr. Jeffrey Trent, president and scientific director of the Translational Genomics Research Institute (TGen).

Prior to forming TGen, Trent had founded and directed the laboratory division of the federal agency in charge of coordinating and finalizing the Human Genome Project.

Trent said that already TGen's work with scientists from around the world has identified a narrow region of chromosome 1 containing a gene that, when broken, gives rise to melanoma—increasing the risk of developing the disease from about 9 percent to greater than 70 percent.

"Now with the completed sequence of chromosome 1 finally in hand, we will hopefully identify a gene that will lead to earlier diagnostics and a potential target for therapeutics," Trent said.

Chromosomes are thread-like structures found in the nucleus of a cell, containing genes that help to determine an individual's characteristics. The human genome has around 20,000 to 25,000 genes. The sequencing of chromosome 1 has led to the identification of more than 1,000 new genes.

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For more information:

"Last human chromosome genome sequenced," MSNBC, 05/18/2006