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Chromosome 21 research brings human genome code a step closer

An international team, including scientists from the University of Geneva, has successfully cracked the code of human chromosome 21, which is linked to Down's Syndrome.

The researchers discovered over 33 million nucleotides, which are like the letters of the genetic alphabet, and an estimated 226 genes.

The research, led by German and Japanese geneticists, started in 1995, and is part of the Human Genome Project. The Swiss team is headed by Professor Stylianos Antonarakis, of the Division of Genetics of the University of Geneva Medical School and the University Hospitals of Geneva, and is funded by the National Scientific Research Foundation.

Antonarakis, who was recently responsible for localising the gene which causes schizophrenia, said that in the same way the anatomy of the human body had been studied in the past in order to find solutions for illnesses, so the anatomy of the human genome could lead researchers to an understanding of genetic diseases.

Chromosome 21 represents a mere one per cent of the human genome, which scientists are still trying to fully identify. However, it is an extremely important part of the human makeup, thought to be responsible for a range of illnesses.

According to the University of Geneva, the 226 genes identified during the course of the research were far fewer than expected; 59 of these were inactive. Most surprising of all for the researchers was that up to a sixth of chromosome 21 contained no genes whatsoever, a unique discovery.

Professor Antonarakis' team localised over 50 per cent of the genes contained in the chromosome, and then identified their characteristics. The scale of the task facing the international team is reflected in the fact that the Geneva research only covered up to four per cent of the total decoding of chromosome 21.

However, the genes are the most important part of the chromosome for future research. Understanding them will enable scientists to make advances in the fight against the diseases associated with the chromosome.

The Geneva team used genetic material donated by the public, and is making the findings available to the wider scientific community. The results of the research will be published in Nature magazine later this month.

swissinfo with agencies