Monday, 25 May 2015

Nature verses Nuture-Its a draw

Polderman TJ, Benyamin B, de Leeuw CA, Sullivan PF, van Bochoven A, Visscher PM, Posthuma D. Meta-analysis of the heritability of human traits based on fifty years of twin studies.
Nat Genet. 2015 May 18. doi: 10.1038/ng.3285. [Epub ahead of print]

Despite a century of research on complex traits in humans, the relative importance and specific nature of the influences of genes and environment on human traits remain controversial. We report a meta-analysis of twin correlations and reported variance components for 1 17,804 traits from 2,748 publications including 1 14,558,903 partly dependent twin pairs, virtually all published twin studies of complex traits. Estimates of heritability cluster strongly within functional domains, and across all traits the reported heritability is 49%. For a majority (69%) of traits, the observed twin correlations are consistent with a simple and parsimonious model where twin resemblance is solely due to additive genetic variation. The data are inconsistent with substantial influences from shared environment or non-additive genetic variation. This study provides the most comprehensive analysis of the causes of individual differences in human traits thus far and will guide future gene-mapping efforts. All the results can be visualized using the MaTCH webtool.


Nature versus Nurture has been a constant issue in the understanding the cause of MS, some favouring a genetic cause and others championing an Environmental cause. We know there is a genetic component and we knew the identity of the main gene region controlling susceptibility to MS long before genome sequencing was thought about. Millions of dollars later and alot of technology later we now that the main gene known is the main gene and that there are 150 others that are known and about a few hundred more to find, which is going to cost more and more as bigger and bigger studies are done. To date little of this knowledge has filtered through to produce treatments, but it may. 

The epidemiology is likewise pretty solid and it is equally clear that there are environmental influences that control many traits including the susceptibility to MS. 

In this study they look at twins and try to work out how their characteristics are determined for identical and non-identical pairs.  
First things they found that there was a congregation of groups doing the studies, so a number of consortia were hoovering up the research cash to do these studies and is not surprising as we know that there groups of people doing these genome studies. The Sanger Centre in Cambridge is one such place. It was set up to sequence the Human Genome, but once this was done rather than stop it was onto the next species...fish etc. These places have infrastructutre for sequencing on a mass scale. The is the International Multiple Sclerosis Genenetics Consortium has multiple members from around the globe.

Anyway in this study they found that heritability of traits was about 50% based on analysis of 15.5 million people in twin studies. So some traits that were looked at were due to the influence of inherited genes. When identical and non-identical twins were compared it was indicated that shared features was related to the number of shared genes so the more shared genes the more likely for a family resemblance. However this was not always the case and some influence of having a shared environment was suggested.

Environment and genetics contribute equally to traits. However, they did find variations in individual traits. For instance, 70 percent of bipolar disorder is due to genetics and other 30 percent can be ascribed to environmental factors. Also, the risk of developing eating disorders was found to be 60 percent environmental and 40 percent genetic.


However if you are more cynical I got an email from someone outside TeamG  "Finally shown! genetics research is a waste of money. Fresh from the press. 50 years of twin studies (14.5 million subjects) show that complex diseases are 50% caused by the environment not the genes. Shall gene sequencing be given up finally? About time we concentrate in epigenetics and biology"

Epigenetics is what happens to influence of how the gene makes its gene product and so with the same gene you can have different influences because the epigenetic (environmental) influences

I am sure the genome mappers would disagree that this should be stopped.

Which sink will the cash go down now... Nature or Nuture? 
I suspect the answer is

It is clear that the environment influences the effect of the genes and genes influence the effect of the environment this study just confirms this.

4 comments:

  1. When they say there are 150 genes linked to MS, and maybe hundreds more undiscovered, do you mean it only takes one of the 150 to trip MS? Or do you mean that I, as an MSer, have all 150 genes?

    ReplyDelete
    Replies
    1. I suspect it is a combination of those genes that puts you at risk none of them means you'll get MS none of them means you won't. They are perfectly normal genes that probably help us fight infection but in a certain combination..the monster arrives

      Delete
    2. Think of it as genes are the gun, nature is the trigger. Dr. Dre will be proud of my mega gangsta analogy, methinks.

      Delete
  2. Are we ever going to really know the cause and effects?
    I've done extensive readig, come across testosterone, cortisol, stress, oxidative stress, ebv, auto immune, glutamine, so much more and it all has support to go with each of the theories
    Which suggests there's no way you guys can cure this, it's almost an impossible task
    The big one that springs to mind though is EBV, ebv mono is touted as a cause of stress, a cause of ocd, even oxidative stress
    Is it as you guys say a case of a multi front approach, to tackle all the issues?
    If it was up to me, HSCT, neuroprotective, attack excess glutamine, oxidative stress and then HAART to take care of ebv

    ReplyDelete

Please note that all comments are moderated and any personal or marketing-related submissions will not be shown.