The human genome contains 3 billion letters but only about 3% codes for proteins -- the rest was tagged as 'junk'. Based on this concept Craig Venter and others set out to create the minimal functional genome with no junk and as reported in a previous blog The Synthetic Wheel of Life, he was able to replace a synthetic yeast genome into a cell devoid of a genome -- and it worked but still contained junk DNA.

Everything changed with ENCODE (Encyclopedia of DNA Elements) -- currently it has been shown up 80% of the DNA is functional and is used to control and modulate gene expression and to make all the different kinds of cells in our body. It is likely that the 80% will go to 100% and there will be no 'junk' DNA.

"Think of the human genome as a city. The basic layout, tallest buildings and most famous sights are visible from a distance. That’s where we got to in 2001. Now, we’ve zoomed in. We can see the players that make the city tick: the cleaners and security guards who maintain the buildings, the sewers and power lines connecting distant parts, the police and politicians who oversee the rest."  (from Discover Magazine)

There are many implications for ENCODE from redefining what is a 'gene' to providing clues as to how the genome works in three dimensions. It gives us a new way to look at diseases and conditions like cancer.