Thousands Of Genes Found To Influence Body Weight

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Thousands Of Genes Found To Influence Body Weighthttp://www.medicalnewstoday.com/articles/94001.phpReporting in the online journal BMC Genetics

, researchers from

the Monell Center have for the first time attempted to count the number

of genes that contribute to obesity and body weight.

The findings suggest that over 6,000 genes - about 25 percent of the genome - help determine an individual's body weight.

" Reports describing the discovery of a new 'obesity gene' have

become common in the scientific literature and also the popular press, "

notes Monell behavioral geneticist G. Tordoff, PhD, an author

on the study.

" Our results suggest that each newly discovered gene is just

one of the many thousands that influence body weight, so a quick fix to

the obesity problem is unlikely. "

To obtain an estimate of how many genes contribute to body

weight, the Monell researchers surveyed the Laboratory Mouse

Genome Database for information on body weights of knockout mouse

strains.

Knockout mice have had a specific gene inactivated, or

" knocked out. " By studying how the knockout mice differ from normal

mice, researchers obtain information about that gene's function and how

it might contribute to disease. Mice can provide valuable information

on human disease because they share many genes with humans.

The knockout approach is so useful that the inventors of the

technology were awarded the 2007 Nobel Prize in Medicine. Knockout mice

are now standard tools in all mouse models of behavior and disease.

In 60% of strains, knocking out a gene produces mice that are

nonviable; that is, the mouse cannot survive without the knocked out

gene.

The Monell survey revealed that body weight was altered in

over a third of the viable knockout stains; 31 percent weighed less

than controls (indicating that the missing genes contribute to heavier

body weight), while another 3 percent weighed more (contributing to

lighter weight).

Extrapolating from the total number of genes in the mouse

genome, this implies that over 6,000 genes could potentially contribute

to the body weight of a mouse.

Tordoff comments, " It is interesting that there are 10 times

more genes that increase body weight than decrease it, which might help

explain why it is easier to gain weight than lose it. "

Because body weight plays a role in many diseases, including

hypertension, diabetes, and heart disease, the implications of the

findings extend beyond studies of obesity and body weight. Gene

knockouts reported to affect these diseases and others could

potentially be due to a general effect to lower body weight.

The findings also hold clinical relevance, according to lead

author le R. , PhD, a Monell geneticist. " Clinicians and

other professionals concerned with the development of personalized

medicine need to expand their ideas of genetics to recognize that many

genes act together to determine disease susceptibility. "

----------------------------Article adapted by Medical News Today from original press release.----------------------------

Maureen P. Lawler also contributed to the study.

The Monell Chemical Senses Center is a nonprofit basic research

institute based in Philadelphia, Pennsylvania. For 40 years, Monell has

been the nation's leading research center focused on understanding the

senses of smell, taste and chemical irritation: how they function and

affect lives from before birth through old age. Using a

multidisciplinary approach, scientists collaborate in the areas of:

sensation and perception, neuroscience and molecular biology,

environmental and occupational health, nutrition and appetite, health

and well being, and chemical ecology and communication. Monell: Making

Sense of Taste and Smell for 40 Years. For more information, visit http://www.monell.org/.

Source: Stein

Monell Chemical Senses Center