'Junk DNA' Plays Crucial Role In Human Diseases
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A lot more of our genome is biologically active than previously thought - about 80% - an international team involving over 400 scientists revealed yesterday. The researchers explained that only approximately 1% of our genome has gene regions that code for proteins, which has made them wonder what is going on with the rest of the DNA. Now that we know that four-fifths of the genome is biochemically active, in a way that regulates the expression of nearby genes, geneticists realize that much less of our genome consists of junk DNA as once believed.
Three Billion Pairs of Genetic CodeSo far, all three billion pairs of genetic code that make up human DNA have been analyzed by ENCODE. Scientists at the European Bioinformatics Institute explained that they have identified the genome function of 4 million gene switches, which will help researchers hone-in on specific areas of human disease, and hopefully find ways to better treat or cure them. They added that the switches are frequently a long way along the genome from the gene they regulate.
Ewan Birney of the European Bioinformatics Institute, lead analysis coordinator for ENCODE, said: "Our genome is simply alive with switches: millions of places that determine whether a gene is switched on or off. The Human Genome Project showed that only 2% of the genome contains genes, the instructions to make proteins. With ENCODE, we can see that around 80% of the genome is actively doing something. We found that a much bigger part of the genome - a surprising amount, in fact - is involved in controlling when and where proteins are produced, than in simply manufacturing the building blocks."
Ian Dunham, also of European Bioinformatics Institute, said that ENCODE is a useful research tool for any researcher looking into human diseases. Scientists investigating diseases often have a good idea about which genes are involved, but need data on which switches play a role. In some cases the locations of these switches are not where they expected them to be. Dunham said "ENCODE gives us a set of very valuable leads to follow to discover key mechanisms at play in health and disease. Those can be exploited to create entirely new medicines, or to repurpose existing treatments."
A principal investigator on ENCODE, Dr Michael Snyder, professor and chair at Stanford University, explained that ENCODE provides us with the knowledge required so that we can look beyond the genome's linear structure to how the whole network is connected. Genome-wide association studies are helping us understand where certain genes are located, as well as which sequences control them. Snyder said "Because of the complex, three-dimensional shape of our genome, those controls are sometimes far from the gene they regulate and looping around to make contact. Were it not for ENCODE, we might never have looked in those regions. This is a major step toward understanding the wiring diagram of a human being. ENCODE helps us look deeply into the regulatory circuit that tells us how all of the parts come together to make a complex being."
Before, generating and storing enormous volumes of data was a problem in biomedical research. However, as productivity of genome sequencing has improved and become more economical, the focus has moved to analysis, i.e. interpreting data generated from genome-wide association studies. Cambridge University scientists said "ENCODE partners have been working systematically through the human genome, using the same computational and wet-lab methods and reagents in laboratories distributed throughout the world."