We had a major discussion before our 2010 paper where I argued that rare variants should have been included. Ten years after there is a nice paper using massive exome sequencing that finally includes them. The respiratory tract isn’t so much influenced by rare variants but there is a strong effect in the immune system.
And there is another interesting fact.
Surveying the contribution of rare variants to the genetic architecture of human disease through exome sequencing of 177,882 UK Biobank participants …if we look at the …. European population who are carriers of a filaggrin (FLG) PTV, we find those carriers have significantly higher risk for well-known associations, such as dermatitis … and asthma … Concomitant increases in vitamin D levels suggest risk of melanoma and basal cell carcinoma in FLG PTV carriers could be attributable to increased sensitivity to ultraviolet B radiation.
So far, I have only assumed some asthma/allergy priming effect of oral vitamin D in the newborn gut.
It is therefore possible to directly quantify the contribution of these genetic variants to phenotypic variance and measure what is called “genomic heritability”. Briefly, the idea is to infer the proportion of variance that can be explained by a linear regression on a set of markers used as explanatory variables.
This genomic heritability seems to be in fact a poor mathematical representation of a biological trait. >1000 hits in >500.000 individuals, does that make any sense at all in terms of biology?
More recently, it was proposed that rather than polygenic, the genetic architecture of common diseases could in fact be “omnigenic” with mainly all active genes affecting every complex traits.
When adding these rare and low-frequency variants to the common variants associated with height, 27.4% of the variation can be explained.
while the results are not impressive. We proposed also structural variants (CNVs), but again no convincing effect so far. Allele dosage? Disappointing . GxE, interaction with genome background? Difficult, highly complex. Epigenetic environmental influences ? Sure but where to start?
The “GIGO (Garbage-In Garbage-Out) syndrome in genetics” as coined by Emmanuelle Génin is one of the main reasons why I mostly dropped out of the field.
We believe that the “missing heritability problem” is an ill-posed problem. Solving it by refining over and over again statistical models derived under the “polygenic paradigm” or using more and more sophisticated sequencing machines will not answer the fundamental and biological question of why that individual is affected by the disease and that other individual is not.
Using data described in Science Magazine (basically 4% of all published books) I constructed a plot showing an update to the 100 year old mystery why we get allergic to certain substances.
There seems to be a good chance for 2011 if the line will further increase…
In this study we investigated serum samples from 944 individuals of 218 asthma-affected families by a multiplex, microsphere based system detecting at high sensitivity eleven asthma associated mediators: eotaxin (CCL11), granulocyte macrophage stimulating factor (GM-CSF), interferon gamma (IFNγ), interleukin-4 (IL-4), IL-5, IL-8, IL-10, IL-12 (p40), IL-13, IL-17 and tumor necrosis factor alpha (TNFα). The largest study so far on serum cytokines weiterlesen →
Allergy Island is an exclusive documentary on the history of asthma in Tristan da Cunha and the discovery of the gene related to asthma in that highly inbred community by the expedition that I did in 1993. I went in May 2008 to Tristan da Cunha with the BBC crew to film both parts for the entire month.
It’s a pleasant experience to write something that is being translated afterwards into so many languages afterwards. It is, however, irritating that this dissemination is irrespective of what I (and all second and third hand journalists and translators) understand of this curious world.
It seems that CEA just published my rather critical view of the recent ORMDL3 association paper. My letter had been first submitted to “Nature” but rejected after review.
A rebuttal seemed to be necessary as the authors repeatedly highlight ORMDL3 as a new asthma gene – in the printed Nature paper, in the Nature podcast and in the accompanying press releases. They even continue with reviews saying that
Completion of the human genome sequence and the advent of genome-wide association studies have resulted in the identification of two novel asthma susceptibility genes, ORMDL3 and CHI3L1, in the past year.
A new abstract at the recent ATS congress now clears the 2007 controversy between the Camargo and Gale studies on the effect of vitamin D: Wheezing is not asthma (as the atopy component is missing?). Not all that wheezes is asthma weiterlesen →