6 September 2012
The most comprehensive analysis of the human genome to date has been published in thirty open access papers across three journals.
The findings of the ENCODE consortium – comprising over 400 researchers working in 32 laboratories across the world – indicate that a much greater proportion of the genome is biologically active than had previously been thought, and should effectively dispel the notion of ‘junk’ DNA.
The results of functional analyses on 147 different cell types demonstrate that at least 80% of the genome performs a specific function – mostly regulating the activity of the 2% that comprises protein-encoding genes. The work identified some 4 million regulatory elements in total, many of which are located far away on the genome from the gene they control.
This is arguably the most significant step forward in our understanding of how the human genome works since the releases of the initial draft sequence in 2000 and the final draft in 2003. At that time it was deeply surprising to many to find that humans possessed only around 20,000 genes occupying less than 2% of the genome, leading some to label the other 98% as ‘junk’ DNA.
Evidence from functional and genome-wide association studies over the years has made this an increasingly defunct term as it became apparent that a large proportion of the single base mutations that cause disease fell between gene coding regions, but this new comprehensive analysis should put an end to the idea once and for all.
Dr Ewan Birney of the European Bioinformatics Institute (EBI) in Cambridge who coordinated the data analysis said “This will give researchers a whole new world to explore and ultimately, it's hoped, will lead to new treatments”. He also pointed out that the job was still far from done, and that deep characterisation is probably only around 10% complete. It is quite possible that much of the remaining 20% of the genome has a functional role that has yet to be identified.