Description: Dark Reapers #eldar #bieltan #gamesworkshop #painting #hobby #warhammer40k #warhammer #miniatures #wh40k #darkreapers
Author: biel_tan on Instagram
Date: October 01, 2014 at 01:10PM
Image Source: Five Years of GWAS Discovery (open access):
The past five years have seen many scientific and biological discoveries made through the experimental design of genome-wide association studies (GWASs). These studies were aimed at detecting variants at genomic loci that are associated with complex traits in the population and, in particular, at detecting associations between common single-nucleotide polymorphisms (SNPs) and common diseases such as heart disease, diabetes, auto-immune diseases, and psychiatric disorders. […]
GWAS studies examine common genetic variants (SNPs) in different individuals to see if any variant is associated with a trait. Since virtually every single behavioural and/or psychological trait ever documented among human beings is found to be heritable, there is some significance to such research.
In the image each marker shows the history of GWAS studies on selected quantitative traits. y-axis = number of variants identified. x-axis = experimental sample size used.
As can be seen, at first there was found to be no genome-wide significant variants affecting height (red circles), this was despite the fact that height (in the developed world) was found to be around ~0.80 heritable (about the same heritability of intelligence):
Only when larger sample sizes were used (>15,000 individuals) did they start to find “GWAS hits” (SNP associations) - tons, in fact.
The graph below again shows the increase in number of variants identified as a function of experimental sample size, this time for selected diseases (chron’s disease, breast cancer, type 2 diabetes, etc):
Similarly, despite its equally high heritability, they’ve yet to discover any common variants for IQ, one of the most complex human traits. It seems they won’t until they pass a threshold in sample size.
Evidently, most complex human traits are polygenic, that is, there are no single variants of large effect (influencing a trait), instead there are many variants (thousands, at least) involved, each with a small effect.
An issue with GWAS studies is the cost:
[…] If we assume that the GWAS results from Figure 1 represent a total of 500,000 SNP chips and that on average a chip costs $500, then this is a total investment of $250 million. If there are a total of ~2,000 loci detected across all traits, then this implies an investment of $125,000 per discovered locus. Is that a good investment? We think so: The total amount of money spent on candidate-gene studies and linkage analyses in the 1990s and 2000s probably exceeds $250M, and they in total have had little to show for it. Also, it is worthwhile to put these amounts in context. $250M is of the order of the cost of a one-two stealth fighter jets and much less than the cost of a single navy submarine. It is a fraction of the ~$9 billion cost of the Large Hadron Collider. It would also pay for about 100 R01 grants. Would those 100 non-funded R01 grants have made breakthrough discoveries in biology and medicine? We simply can’t answer this question, but we can conclude that a tremendous number of genuinely new discoveries have been made in a period of only five years. […]
Consider this: the variation in complex human behavioural traits are not accounted for by the effects of the shared-environment, that is, any influence from “nurturing” (parenting, community, teachers, general upbringing and so forth) — the factors which most often dictate expensive governmental policy and social reforms — have in fact, been consistently shown to be very small. Such factors only exist with minimal influence in adolescence, (any parental influence on IQ rapidly diminishes with age with no notable effect on adult intelligence) and have insignificant (even close to statistically zero) impact on how we eventually turn out on any measure of human traits (political ideology, social attitudes, religiosity, etc).
Despite what those useless correlation studies (that don’t even bother assessing causation) in the press say about the impact of parenting on individual outcomes, once heredity is controlled for, it’s the genes individuals share, not examples set by their parents, that explains any relationship between parents and their biological children, e.g., on whether such individuals turn out to be smokers, engage in anti-social behaviour, or just end up being tall.
Behold Tom’s Botox face.
French soldiers on a break during a walk. 1914.