Fat is a genetic issue, worm study reveals

The reason why some people are born to be thin while others are overweight might soon be answered with the help of a microscopic worm and an importantgenetic discovery.

The reason why some people are born to be thin while others are overweight might soon be answered with the help of a microscopic worm and an importantgenetic discovery.

Scientists have identified more than 400 genes involved in the metabolism of fat after a study of the nematode worm and RNA interference (RNAi), a powerful technique for finding out what a gene does.

They believe many of these genes – some of which lead animals to put on weight, others to lose it – exist in humans, raising the prospect of new treatments for clinical obesity.

The researchers, led by Julie Ahringer of Cambridge University, used RNAi to analyse each nematode gene one by one, the first time such a systematic analysis has been made on an animal.

Dr Ahringer said the usual way of determining the function of each gene involved a painstakingly slow procedure taking up to six months. "What we've done is to ... find out very quickly what a gene does. What took six months for one gene can now take a few months for the entire genome," she said.

The research, published today in the journal Nature, involved the creation of thousands of strains of genetically engineered bacteria. Each strain was designed to block a specific gene using RNAi.

By feeding each strain to nematodes, the scientists, in collaboration with Harvard Medical School, were able to block selectively the function of individual genes from a list of about 17,000 and observe the effect this had. They found that 305 genes reduced body fat and 112 increased it.