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Study Shows Some Morbidly Obese People Are Missing a Section of DNA
By Jennifer Warner
WebMD Health News
Reviewed by Louise Chang, MD
Feb. 3, 2010 — Missing genes may be behind at least some cases of morbid or
extreme obesity, according to a new study.
Researchers found that a small but significant portion of morbidly obese
people are missing a section of their DNA that may contribute to their obesity.
The results suggest around seven in every 1,000 morbidly obese people are
missing this section of their DNA, which contains about 30 genes. This genetic
variation was not found in any people of normal weight.
“Although the recent rise in obesity in the developed world is down to an
unhealthy environment, with an abundance of unhealthy food and many people
taking very little exercise, the difference in the way people respond to this
environment is often genetic,” says researcher Philippe Froguel, of the School
of Public Health at Imperial College London, in a news release.
Overall, researchers say about one in 20 cases of morbidly obese people is
caused by genetics, including previously identified genetic mutations and these
missing genes. But many more genetic mutations linked to obesity are yet to be
The researchers hope that identifying genetic variations that cause people to
be morbidly obese will lead to the development of genetic tests that can help
determine the best treatment.
“If we can identify these individuals through genetic testing, we can then
offer them appropriate support and medical interventions, such as the option of
weight loss surgery, to improve their long-term health,” says Froguel.
In the study, published in Nature, researchers first identified the missing
genes in teenagers and adults who had learning difficulties or delayed
The results showed 31 people had nearly identical deletions in one copy of
their DNA. All of the adults with this genetic variation had a BMI of over 30,
which means they were obese.
People inherit two copies of their DNA, one copy from their mother and one
from their father. Sometimes one copy of one or more genes is missing and can
affect a person’s development, as shown by this study.
In the second part of the study, researchers examined the genomes or genetic
maps of 16,053 European people who were either obese or normal weight. They
found 19 more people with the same set of missing genes. All of these
individuals were morbidly obese.
The study showed people with the genetic deletion tended to be normal-weight
toddlers who became overweight during childhood and morbidly obese as adults.
Researchers did not find the genetic deletion in any normal-weight people.
Although they do not know the function of the missing genes, previous studies
suggest some of them may be involved with delayed development, autism, and
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Walters, R. Nature, Feb. 3, 2010, online advance edition.
News release, Imperial College London.
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