'Gene Overdose' Causes Extreme Thinness

ScienceDaily (Aug. 31, 2011) — Scientists have discovered a genetic cause of extreme thinness for the first time, in a study published August 30 in the journal Nature. The research shows that people with extra copies of certain genes are much more likely to be very skinny. In one in 2000 people, part of chromosome 16 is duplicated, making men 23 times and women five times more likely to be underweight.

Each person normally has a copy of each chromosome from each parent, so we have two copies of each gene. But sometimes sections of a chromosome can be duplicated or deleted, resulting in an abnormal 'dosage' of genes.

In a study examining the DNA of over 95,000 people, researchers at Imperial College London and the University of Lausanne have identified that duplication of a part of chromosome 16 is associated with being underweight, defined as a a body mass index below 18.5. Half of all children with the duplication in the study have been diagnosed with a 'failure to thrive', meaning that their rate of weight gain is significantly lower than normal. A quarter of people with the duplication have microcephaly, a condition in which the head and brain are abnormally small, which is associated with neurological defects and shorter life expectancy. Last year, the same researchers discovered that people with a missing copy of these genes are 43 times more likely to be morbidly obese.

Professor Philippe Froguel, from the School of Public Health at Imperial College London, who led the study, said: "The dogma is that we have two copies of each gene, but this isn't really true. The genome is full of holes where genes are lost, and in other places we have extra copies of genes. In many cases, duplications and deletions have no effect, but occasionally they can lead to disease.

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http://www.sciencedaily.com/releases/2011/08/110831160038.htm

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is pointed directly at the parents, their ability and willingness to be competent caregivers. This discovery should help remove the stigma attached to that diagnosis.

:)

Both of my sons are thin, always have been. Especially the older one. I used to joke that I always needed witnesses around when I fed them, because to look at them you couldn't be sure I was doing it regularly.

I have no idea if they have this particular gene, but it might be a possibility.

that is a dearth of these genes, one cause of obesity?

Article doesn't say, just wondering out loud.

"Last year, the same researchers discovered that people with a missing copy of these genes are 43 times more likely to be morbidly obese."

Of course, don't put this in GD because you will be told that ONLY too many calories can cause obesity.