Working out the sequence that makes up genetic code is now routine in medical research, but the sequence is not the whole story; genes are also turned on and off by physical interaction between specific parts of DNA.
Consider chromosome 1, just one of the 23 paired chromosomes we have: An intricately folded chain of 250,000,000 nucleotides containing 4,220 genes which physically interact with each other in three dimensions.
Read more (Oxford Science Blog, University of Oxford website)