The gene code. Part 2, Unlocking our code.

The second in a two-part series in which genetist and science journalist Adam Rutherford looks in depth at DNA. In this part, Rutherford asks how decoding the 'book of life' (the human genome) helps us understand who we are. He explains what DNA is. A biologist, Hugh Young Rienhoff, from America used home-diagnostic kits to ascertain his daughter's unique and unknown genetic condition. Next, Rutherford goes back 50 years to the work of Crick and Watson, the discoverers of the double helix shape. A physicist interested in how the amino acids interacted, George Gamow, contacted Crick and Watson to further this work. Then, in the US, two young scientists, J. Heinrich Matthaei and Marshall Warren Nirenberg discovered a combination of acids which made a single protein; this became the 'Rosetta Stone' of DNA. Rutherford asks how our DNA effects variation in our hereditary such as hair colour. Professor Kay Davies then discusses Muscular Dystrophy which effects boys and leads to poor muscle tone, disability and limited life expectancy. This has led to accurate pre-natal diagnosis. However, being diagnosed with a genetic disease is not easy. Former war correspondent, Charles Sabine, discusses his diagnosis of Huntingdon's Disease which always leads to mental impairment and then death. All these disease are rare; they are known as mono-genic. Rutherford considers height which is poly-genic. The interactions between the genes is commonly known as 'Sanger-sequencing' after the Nobel prize winning researcher, Fred Sanger. Rutherford illustrates this using a pack of playing cards. By 2001, decoding the entire human genome was completed. Dr Ewan Birney talks to Rutherford about his work discovering how many genes we actually have. He provides evidence illustrating how diverse estimates were at the time; there are in fact around 24,000 in humans. Within the human genome it was discovered that 98% of our DNA could be 'junk'. Professor Peter Donnelly, director, of the Wellcome Trust Sanger Centre, describes how we are more similar than different. In a project that studied both sick and well people, seven common disease such as coronary heart disease and diabetes are shown to be genetic in nature. This does not take into account the environment such as exercise and diet. Dr Claire Howarth talks about twins and her studies in various traits such as height. Many traits are highly hereditable, but not in evidence in the mapped genome, known as 'missing hereditability'. Current thought is that some of this data will be in the 'junk' DNA. Professor Mark McCarthy from the University of Oxford uses new technology to look at diabetes sufferers and see what further variants can be discovered. Ewan Birney then talks about the project ENCODE; to form an encyclopaedia of DNA. He describes the choreography of the molecules which form a much more complex relationship. The dark matter of DNA looks to be more important, indeed the shape itself seems signifcant.