THE FARM REVEALED
PROGRAMME 2: DNA SEQUENCING AND ANALYSIS
BACKGROUND
One of the first applications of human DNA profiling was in forensics. DNA fingerprinting, or profiling, was first developed by a hugely talented molecular biologist at Leicester University called Alec Jeffreys (now Sir Alec Jeffreys).
In 1986, two girls were raped and murdered in Enderby, near Leicester. When a suspect confessed to one of the murders, the police approached Alec Jeffreys for help. Jeffreys took semen samples from the girls' bodies and profiled the DNA. He also profiled the suspect. The suspect, it turned out, had committed neither of the murders. And so, the first forensic use of genetic fingerprinting was actually used to prove innocence, not guilt. Following this, the first DNA-based manhunt ensued and the police took 5,000 blood samples from local Enderby residents. Eventually, the murderer was discovered by a match to the DNA from the semen samples.
Since 1986, DNA profiling has progressed to the point that all convicted criminals are included in the National DNA Database. DNA profiling is, of course, also important in paternity cases. In fact, profiling has applications in any situation that involves identifying someone, or identifying their blood relations.
Of equal significance is the application of DNA biotechnology to medical science. Current UK estimates of the overall incidence of genetic disease arising at birth runs at 2-3% and rises to 5% by the age of 25. An understanding of the genetics of these conditions opens up the possibility of much better drug treatments. Some of the most famous genetic diseases are cystic fibrosis, Duchenne Muscular Dystrophy and Huntington's Disease. Other diseases like Parkinson's and some forms of bowel and breast cancer have been shown to have genetic components. Understanding these disease genes has improved some drug therapies, but progress is slow and none of them are 100% curable at this time.
The genetics of behaviour, particularly human behaviour, is a much more woolly area than disease genetics. For example, the gene encoding the DRD4 dopamine receptor has been implicated in many diverse behaviours such as ADHD, intellectual ability, sexual behaviour, illicit drug use and tobacco smoking in boys. One gene cannot possibly be wholly responsible for all these varied behaviours. Most studies of human behaviour and genetics are very difficult to interpret because they involve multiple genes and environmental influences. There are between 30,000 and 40,000 genes in the human body and scientists are nowhere near the day when they will be able to use them to predict your behaviour accurately.
