An entire network of genes in the body is disrupted by overeating and this not only causes obesity, but also diabetes and heart disease, according to the March issue of Nature.
Eric Schadt, executive director of genetics at Merck Research Laboratories, and colleagues developed a new method of analyzing DNA and used it to reveal that obesity is complex in ways that had not been previously understood.
Schadt said obesity is not a disease that is the result of a single change to a single gene—it changes entire networks.
The investigators identified networks of hundreds of genes that appear to be disrupted when mice were exposed to a high-fat, western diet.
When the researchers examined a database of Icelandic people being studied by Decode Genetics, they discovered people have the same networks.
The results showed that people, who have a higher body mass index and a measurement of obesity, have characteristic patterns of gene activation in their fatty tissues not seen in DNA taken from blood, according to the authors.
The investigators said their results illustrate that the common forms of the diseases are very complex and simple genetic tests cannot detect these networks. Also, some people have networks that predispose them to diabetes when they become obese, others to high cholesterol and clogged arteries and some network patterns appeared to predispose some people to metabolic syndrome.
The team said that the diseases of obesity appear to originate in the immune system and the network is enriched for genes that are involved in macrophages.
Schadt said his team now hopes to study the networks and identify the genes most likely to cause the disease which could lead to new drugs designed to target their activity.