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Pooka1
11-18-2009, 05:53 AM
http://www.ejbjs.org/cgi/content/abstract/88/10/2133

Conclusions: In a large cohort of twins that included almost 35,000 individuals, the self-reported overall prevalence of Scheuermann disease was 2.8% and the male-to-female ratio was close to 2:1. Because the pairwise and probandwise concordance and the odds ratio were two to three times higher in monozygotic than in dizygotic twins and the heritability was high, we concluded that there is a major genetic contribution to the etiology of Scheuermann disease.


Of course this is again self reportage so we have no idea how good this conclusion actually is.

Can someone find out the ratio of identical to fraternal in this large Danish cohort? That would cut right to the chase on certain issues. I am betting the ratio is WAY off which means all these published papers are WAY off.

Don't believe me... check of the Olsen Twins and their "reasons" they use to conclude they are fraternal. No reason to think this is unusual.

Dingo
11-18-2009, 08:36 AM
Because the pairwise and probandwise concordance and the odds ratio were two to three times higher in monozygotic than in dizygotic twins and the heritability was high, we concluded that there is a major genetic contribution to the etiology of Scheuermann disease.

All of that information sounds plausible. But there is a world of difference between genetic contribution i.e. susceptability and genetic disease.

The truth is that genetic susceptability may be a factor in all human disease including our risk of contracting flu virus (http://www.sciencedaily.com/releases/2009/10/091025200248.htm). Does anyone consider the flu a genetic disease?

Here is a page that lists 28 different common diseases and their genetic risk. Health Scan Report (http://www.genomealberta.ca/files/Personal_Genotype_Files/Decode_Genotyping_Summary.pdf)

No matter what the disease, disorder or even accident is if scientists look for genetic susceptability they are almost certain to find something.

Bonus Point:
Evidently genetics are even a factor in car wrecks (http://www.scoliosis.org/forum/showthread.php?t=9548).

Pooka1
11-18-2009, 01:16 PM
Scoliosis and kyphosis occur at a frequency of 2-3% in the population. I mention this only because you think it is some master variable.

Yet the Danish Twins study produced wildly different concordance results for these two conditions.

How can both results be plausible?

Pooka1
11-18-2009, 01:45 PM
I have been trying to find the ratio of (self-reported) mono/di twins in the Danish registry. I can't seem to find this figure anywhere.

Hmmmm. It seems like this would be one of the main quality control data checks of the database but I can't find it on the registry site.

One wonders if the ratio is wildly different from the expected ratio.

Possibly the main registry doesn't determine zygosity and only the papers done on certain subpopulations try to determine zygosity. That could be the case.

I think the MOST interesting result possible out of this registry is to provide data for what has been a repeated observation... most people don't have a clue about what can be used to determine zygosity and especially what can't be used.

mamamax
11-18-2009, 10:00 PM
Dingo & Sharon

I'm way out of my league on all this - but, wanted to offer this article to both of you - it seems to be thorough and well referenced.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2674301/

Dingo
11-18-2009, 11:25 PM
Mamamax

Great study, thanks! One sentence stood out for me.


These observations may be most consistent with a multifactorial inheritance model involving several to many genes, interplaying with unknown environmental factors.

Whatever the environmental factor is it has to have been around for thousands of years. As time goes on my confidence that the problem is in some way triggered by an infection grows.

Pooka1
11-19-2009, 05:45 AM
Dingo & Sharon

I'm way out of my league on all this - but, wanted to offer this article to both of you - it seems to be thorough and well referenced.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2674301/

Very pertinent.

I'm reading this and will respond later. Gotta run now.

Pooka1
11-20-2009, 05:59 AM
Dingo & Sharon

I'm way out of my league on all this - but, wanted to offer this article to both of you - it seems to be thorough and well referenced.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2674301/

Okay I read this article and can't really evaluate most of the science (as is the case for virtually all these scoliosis articles).

But I want to say I like the writing style, especially the use of particular words. The tone is one of open-mindedness and open-ended discussion with a rigorous effort to avoid preconceived notions, pet theories, data selection, etc. No hint of any party line. Exemplary.

I note how they have to mention and then immediately shoot down the Danish Twins study for the same reasons I have been mentioning. Every once in a while you get this kind of situation where a paper is published that shouldn't be and it produces aberrant results due to inappropriate methodology and inadequate QA/QC. But because the results are aberrant, and because aberrant results are sometimes instructive (given adequate methodology and QA/QC), you have to mention the study and then see if there is a plausible reason for the aberrant results.

There is a case in my field of a paper that should not have been published and had aberrant results because of bad methods and inadequate QA/QC and people have to bring it up and shoot it down in subsequent pubs.

It's annoying when bad papers get through peer review because they waste not only the original journal space but also all the subsequent mentions in other articles.

In the case of the Danish Twins study, the two QA/QC parameters (incidence of scoliosis and ratio of mono/di twins) should have been used to reject the paper as garbage in - garbage out.

concerned dad
11-20-2009, 08:11 AM
I've been waiting for a good excuse to share this.

You may find this interesting and amusing (http://scienceblogs.com/catdynamics/upload/2009/08/how_to_publish_a_scientific_co/How%20to%20Publish%20a%20Comment.pdf).

:D
CD

Ballet Mom
11-20-2009, 10:43 AM
Dingo & Sharon

I'm way out of my league on all this - but, wanted to offer this article to both of you - it seems to be thorough and well referenced.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2674301/

Mamamax,

You're posting such great studies!

This study certainly seems to leave room for both the genetic basis and environmental factors together causing scoli and/or progression.

Thanks for posting....very interesting.

Pooka1
11-20-2009, 12:24 PM
I've been waiting for a good excuse to share this.

You may find this interesting and amusing (http://scienceblogs.com/catdynamics/upload/2009/08/how_to_publish_a_scientific_co/How%20to%20Publish%20a%20Comment.pdf).

:D
CD

Amazing, isn't it?

There are relative few comment papers published in my field at least. I suppose they have to limit them for the medical literature as every non-controlled study would trigger a comment otherwise. And that's like virtually every one. :D

I would submit a comment on that Danish Twins study if it wasn't published two years ago.