Human gene catalogue unveiled

A new database of over 21,000 human genes has been released by an international team of scientists. The new resource, details of which are published in the free journal Public Library of Science Biology (PLoS), should prove invaluable in the search for genes involved in disease, says project leader Takashi Gojobori. The so-called H-invitational database is being hailed as a major advance in efforts to identify and understand the information contained within the human genome sequence.

An international consortium unveiled the final version of the entire human genome on 14 April 2003. But this sequence of 2.9 billion chemical 'letters' of DNA is made up of vast amounts of 'non-coding' DNA, as well as the 'coding' DNA that makes up genes. Scientists have used computer programs to look for genes, which predict likely sections of coding DNA in the genome, and have estimated that it contains between 25-30,000 genes. But a more reliable way of identifying genes is to isolate different types of another chemical, called mRNA (messenger RNA), from body tissues. mRNA is an intermediate stage between a gene, and the protein it codes for - the cell uses an mRNA template when making a protein, rather than reading the DNA code directly. Since mRNA molecules are unstable and not very easy to study in the laboratory, researchers make DNA copies of individual mRNA molecules, called complementary DNA (cDNA).

The new database is the result of a detailed analysis of 41,118 existing cDNAs, which the researchers have compared with data from the human genome sequence. They have so far catalogued cDNAs representing 21,037 working genes, including details of 5,155 previously unknown genes. The work was carried out by 158 top genome scientists from 67 institutions in 12 countries, over ten days in summer 2002. The event was called the 'Human full-length cDNA annotation invitational' - H-invitational' - says Gojobori, 'because we only wanted the best genome scientists to participate to ensure a high standard of quality'. An article accompanying the PLoS Biology paper says: 'This study not only moves us closer to a complete functional description of the human genome, it also builds on the traditions of international co-operation and large-scale collaboration that played such an important part in deciphering the sequence itself'.