Posts Tagged ‘Heritability’

Some call it “phantom heritability” while others call it “dark matter” … whatever … genes are definitely not “beans in a bag” that independently add up to influence development.  They interact in complex bio-physical-3D-proteo-ribonucleic-tertiary-etc.-etc. ways.

“Ultimately,” they concluded, “the most important goal for biomedical research is not explaining heritability — that is, predicting personalized patient risk — but understanding pathways underlying disease and using that knowledge to develop strategies for therapy and prevention.” [paper]

Note to self: Abandon any musings of future employment in the “predicting personalized patient risk” business … unless someone comes up with a useful model that helps best fit these interactions.

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Hey Yin, we have a genome and a brain … what’s the relaionship?

I dunno Yang.  Lets focus on variation.  Genome sequence variation can vary with the brain  … and … gene expression can vary with the brain  … however … genome sequence variation can vary with gene expression … but … here’s a paper showing that gene expression is under the control of genome sequence variation. Purrrr.

Hey Yin, the correlation between genome sequence variation and gene expression confuses me.  I mean, gene expression can change if the environment changes right?  Doesn’t this confound research that uses genome sequence variation?


thanks for the pic noyfb.

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Probably not … but perhaps genes that predispose to certain personality or cognitive traits that help/hinder our ability to form stable social bonds.

“Several demographic variables including marriage, having siblings and children and educational attainment explain part of the variance in loneliness. Genetic factors, both additive and non-additive, explain about 37% of the variance.”

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“Listen Eric, you should think about how useful your newfangled Personal Genome is going to be.  There are a lot of reasons why all this information doesn’t tell you much”

“For example, have you thought about epigenetic effects that might be environmentally induced and can be transmitted across multiple subsequent generations?  Genotypes of individuals in previous generations might even be a better predictor of phenotype than an individual’s own genotype.”

“I know that Copy-Number Polymorphic (CNP) duplications are highly variable among individual and are considered inaccessible by most existing genotyping and sequencing technologies, but I’m still getting my genome sequenced anyway.”

“Can you please help Eric understand that rare variants and large variants (deletions, duplications and inversions) are individually rare, but collectively common in the human population might account for much more of heritability than common variation.  Nothing is known about these rare variants!”

“Yeah, Eric doesn’t realize that a very large number of closely linked genes can exhibit context-dependent and non-additive effects.”

“Gene by environment innnterraaaaactiiooon … coooool.”

–real science here.

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A sculpture of a Hindu yogi in the Birla Mandi...
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This past friday, I attended my first meditation session at my new yoga school.  I love this school and hope – someday – to make it through the full Ashtanga series and other sequences the instructors do.  In the meantime, I found myself sitting on my folded up blanket, letting my mind wander, listening to my breath and just trying to enjoy the moment.

What a wonderful experience it was … it felt great!  … I think I my have even given my brain a rest. A simple kindness to repay it for all it has done for me!

Although I did not know what I was supposed to be “doing” during meditation, the experience itself has me hooked and fascinated with a new research article, “Genetic control over the resting brain” [doi: 10.1073/pnas.0909969107]  by David Glahn and colleages.

Reading this paper, I learned that my brain “at rest” is really very active with neural activity in a series of interconnected circuits known as the default network.  Moreover, the research team finds that many of these interconnected circuits fire together in a way that is significantly influenced by genetic factors (overall heritability of about 0.42).  By analyzing the resting state (lay in the MRI and let your mind wander) patterns of activity in 333 folks from extended pedigrees, the team shows that certain interconnections (neural activity between 2 or more regions) within the default network are more highly correlated in people who are more related to each other.  For example, the left parahippocampal region was genetically correlated with many of the other brain areas in the default network.

Of course, these genetic effects on resting state connectivity are far from determinative, and the authors noted that some interconnections within the default network were more sensitive to environmental factors – such as functional connectivity between right temporal-parietal & posterior cingulate/precuneus & medial prefronal cortex.

Wow, so my resting state activity must – at some level – as a partial product of my genome – be rather unique and special.  It certainly felt that way as my mind wandered freely during meditation class. The authors point out that their heritability study lays more groundwork for follow-up gene hunting expeditions to isolate specific genetic variants.  This will be very exciting!

Some other items from their paper that I’ll be pondering in my next meditation class are the facts that these default neural networks are already present in the infant brain!  and in our non-human primate cousins (even when they are not conscious)!  Whoa!  These genetics & resting-state brain studies will really push our sense of what it means to be human, to be unique, to be interconnected by a common (genetic) thread from generation to generation over vast spatial and temporal distances (is this karma of sorts?).

I suppose yogis & other practitioners of meditation might be bemused at this recent avenue of “cutting edge” scientific inquiry – I mean – duh?!  of course, it makes sense that by remaining calm and sitting quietly that we would discover ourselves.

Related posts here, here, here

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