How fat genes differ from thin ones

Erika Check

Growth area: resequencing, used here to investigate the genetics of body size, is getting to be big. Alamy

Researchers have used a new technique to hunt for rare genetic quirks that explain why some people are extremely fat or very thin.

The researchers, led by Len Pennacchio of the Lawrence Berkeley National Laboratory in California, studied 757 Canadians from Ottawa. Half of the participants were chosen because they were fatter than 95 of the general population for their height: on average they weighed 125 kilograms. The other half was thinner than 90% of the population, with a mean weight of 57 kilograms.

The team examined 58 genes known to be related to obesity, appetite, or the conversion of food into energy, in every participant. They looked for tiny differences between people in the series of chemical building blocks that make up each gene. This technique, called medical sequencing or resequencing, aims to discover rare genetic variations that may subtly influence particular traits - including body size.

Most previous genetic trawls have focused on using the HapMap - a catalogue of common genetic variants shared by most people with a certain disease. Resequencing is different, as it looks for genetic quirks that are unique to just a few individuals. Resequencing studies have been used to find variations that may cause cancer¹ and differences in cholesterol², whereas HapMap studies have been used to hunt for more common variations that contribute to a range of conditions, including diabetes

http://www.nature.com/news/2007/070312/full/070312-9.html