The human genome: into uncharted territory

The completion of the sequencing of the human genome in April of this year was a massive achievement but just the start of the hard work involved in determining the function of all the sequences it contains.

While efforts to decipher the protein-coding regions of the genome are attracting the most attention, the non-coding regions, often still dismissively referred to as 'junk' DNA, are now the focus of a new program to ascribe function to the entire genome map.

The ENCODE (ENCyclopedia Of DNA Elements) program is designed to determine the identity and precise location of all of the protein-encoding and non-protein-encoding genes in the genome. The latter - which is estimated to make up around 95 per cent of the entire genome - contains regulatory sequences, such as origins of replication and promoters of transcription, as well as now-defunct genes and gene fragments cast aside during evolution and viral genetic material.

"A comprehensive encyclopedia of all of these features is needed to fully utilize the sequence to better understand human biology, to predict potential disease risks, and to stimulate the development of new therapies to prevent and treat these diseases,"​ according to the US National Human Genome Research Institute (NHGRI​),which is coordinating the programme.

Earlier this month, the first grants were allocated by the NHGRI to researchers involved in the ENCODE project, which has an initial budget of $36 million (€30m) over the next three years. It will involve scientists from academia, government and industry and will focus at the outset on determining efficient, high-throughput methods for identifying, locating and fully analysing all of the functional elements contained in a set of DNA target regions that covers approximately 30 megabases, or about 1 per cent, of the human genome.

If the pilot effort proves successful, the project will be expanded to cover the entire genome.

"The Human Genome Project has provided us with a wonderful foundation, but obviously having the human genomic sequence is not enough. We must keep on exploring this newfound wealth of knowledge if we are to realise the full potential of genome research to improve human health,"​ said NHGRI director Francis Collins.

In addition to studying the human genome itself, another component of the ENCODE project will be the comparison of genomic sequences from many different animals. Finding DNA sequences that have been highly conserved throughout evolution is a strong indicator that these sequences reflect functionally important regions of the human genome.