Thursday, February 4, 2016

Fat? Thin? Molecular switch may turn obesity on or off

Identical twins are usually alike in everything but; can diverge in one important characteristic, their weight. A new study uncovers a molecular mechanism for obesity that might explain why in twins, one can be extremely over weight even while the other is thin.

Heredity influences whether we become obese , gene researchers have found this link but yet doesn't explain the many differences in weight among people. Identical twins with non-identical weights are a prime example.

Researchers are now taking a closer look at this phenomena to see what accounts for this variation. Could it be changes in the intestinal micro-biome (Collection of bacteria living in the gut) or is it epigenetic changes (Alternations in gene activity)? These changes occur when molecules latch on to DNA proteins, turning sets of genes "on" or "off". Triggered by the factors in the environment, epigenetic modifications can be passed down from one generation to the next.

Physiologist J. Andrew Pospisilik of the Max Planck Institute of Immunobiology and Epigenetic's in Germany noticed an odd pattern of weight gain in mutant mice. After DNA testing the mice only had one copy of a gene called Trim28, the researcher found that most of them were obese. Trim28 is an epigenetic modifier which implicates it is a major gene in the bodies weight management. The exact functions remain unclear, but Pospisilik and colleagues hypothesize that Trim28 helps form an epigenetic switch that can flip on obesity by suppressing these genes.

Could this be the same mechanism to cause obesity in humans?

 The thing is mice only have one copy vs humans who have two. To compare, the team took fat samples form obese children in hospitals as it turns out Trim28 activity was abnormally low in those kids. The researchers then analyzed data on 13 pairs of identical twins in which one twin was obese.

Trim28 was diminished in the fat of the obese twin,  could this be the key to obesity ? This opens up the possibility of DNA screening at birth to see in fact if that new born will be obese.

This study gives a new potential mechanism of obesity and is a step closer to prevent or even reverse the condition of obesity.


  1. Robert, this is a very interesting post! We all know that obesity can be genetic, but most of us forget it. I have never thought about one twin being obese and one not, which is so strange. After reading your article, it seems so strange to me that one identical twin could be obese because of their genes, and one can not. Epigenetic genes are very cool because they can ultimately turn a gene on or off, which is triggered by the environment. It makes me question what elements in the environment can trigger a response, like turning off gene activity. The finding of the Trim28 in mice is definitely a huge step in figuring this phenomenon out. From your explanation, it seems like there is still a lot to figure out before discovering the real cause of this obese gene in only one identical twin. I like how this finding opens up the possibility of DNA screening at birth to see if the child will be obese, but I do not really see a purpose in that. What could the parents do if they found out their child has a good chance of becoming obese? Give them away? Put their newborn on a diet? I just do not really see the use in the DNA screening, because it will only upset the parents knowing there is not much you can change about genes. Overall, I thought it was a really interesting article, and an awesome find and only shows how more and more advanced science is getting!! It made me question things that I never would have without reading this. Great job!

  2. This is extremely interesting, and no doubt will one day lead to a scientific market for health gains by genetic modifications.

    However i can see the negatives of this, such a culture that may one day shame the overweight rather than promoting self acceptance. While the two are co-related, It is possible for someone that is overweight to not have any significant health issues. To instill at birth to a child that they are destined to be overweight and socially inferior is not right. I can see some parents getting carried away with this and doing more harm, than good for a child.