The genes of animals usually contain extra bits of DNA sequence, called introns “ regions that are removed before cells make their proteins. Humans have many introns in their genes, while common animal models such as flies have fewer. From an evolutionary perspective it was long assumed that the simpler fly gene organization would be more ancient. The new study reveals the opposite: early animals already had a lot of introns, and quickly-evolving species like flies have lost most of them.

Worm-like creatures which lived more than 550 million years ago are thought to be the last common ancestor of almost all living animals, including worms, flies and humans. In order to better understand the genetic make-up of this creature, the team sequenced part of the genome of a living marine worm, Platynereis dumerilii, which has very similar characteristics. They found that Platynereis genes have almost the same number of introns as humans (often in the same place), and many more than insects.

We conclude that at least two-thirds of human introns already existed in our ancient ancestor, ™ said Dr Ferrier. This shows that rather than genes getting more complex over the course of evolution, they were already quite complex in the earliest animals. The use of Platynereis will help us to build a picture of the organism that lived more than 550 million years ago, from which most of the diverse forms of animals that we see around us today evolved. ™

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Genetic association studies are inconclusive with regard to the best genetic candidates in the smoking cessation field The responsibilities of general adult psychiatrists, substance misuse service professionals and general practitioners are already significant, without the additional burden of informing themselves about, and providing counselling on, gene-based therapies The cost implications for the NHS of this added duty is of concern Current privacy laws within the UK fail to protect patients from the misuse of genetic information. Many European countries have laws preventing insurers and prospective employers from gaining access to an individual's genetic profile. When patients spend money on a genetic test for smoking cessation, they are inadvertently generating information about their risk of predisposition to developing or possessing a number of other stigmatising conditions, such as alcohol or cocaine addiction, or pathological gambling The majority of people who attempt to give up smoking using genetic tests will fail -success rates are as low as 20% in a year Information provided to patients from the test may mislead them into thinking they have a particularly virulent or 'genetic' form of addiction, and are never going to be able to give up.

The authors of the editorial conclude that more research is needed to verify the usefulness of genetic tests for smoking cessation, especially among general medical and psychiatric patients.

Until there is greater understanding of the genetic influences in nicotine addiction, patients being cared for in psychiatric services are best advised to avoid such tests.

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