The deeper scientists look into the human genetic code, the more baffling it becomes but it is also increasing their understanding of disease. Seven years ago, with much ballyhoo, scientists unveiled the book of life - the DNA required to build and run a human being. Last week, a small army of geneticists reported the results of the first systematic attempt to make sense of this book. What they found makes uncomfortable reading for those who thought they understood the basics of biology, but it does provide tantalising hints of new ways to fight disease. This, the most detailed study of DNA, is a landmark in genetics research, for the more scientists understand the details of how our bodies work, the easier it will be to fix them when they go wrong. But the latest findings turn basic biology concepts upside-down, could rewrite conventional wisdom when it comes to common ailments, and contain many puzzles, including one that may even challenge our understanding of the way evolution works.The basics of genetics go like this: DNA, or deoxyribonucleic acid, is a long chemical that is coiled up in sausage-like bundles, called chromosomes. Two metres of DNA are crammed this way into the chromosomes within a single cell. DNA is a ladder-like molecule twisted into a double helix, where the rungs consist of chemical units, called nucleotides. These units are drawn from an alphabet of life that consists of only four letters - A, T, C and G (see graphic) - so the code reads GGGAAACCC and so on for around three billion letters, the entire complement, or genome, of one set of chromosomes. (Telegraph)
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