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10:06 am: Warrior gene, not so much
My friend atgatg found a solution for my question of what he terms the 'manliness' gene! I will briefly protest that neither are all belligerent hot-sauce administering warriors men, nor are all men warriors, and then move on.

The solution is to use some of that basic genetics knowledge that I should have remembered from the early 2000's.

The key is that while we can't use the SNPs to directly measure the trait in question, we can take advantage of the fact that they are located on that same relatively small chunk of DNA. These SNPs associate with this particular mutation, meaning merely that they tend to vary along with it. If we assume that the SNPs will vary - give or take - at the same rate as the tandem repeat, and if we can find someone who measured both the SNPs and the trait on a decent sized population, then we might be back in business. As he says: it wouldn't do for the block to be coherent *except for* the one variable little piece that actually matters.

Once again, we bang up against that annoying definition of "genes." I'm now dragging in some other study about a different thing. This is, in the very small, why good scientists are so very thorough and paranoid about making declarative statements.

Anyway, here's his answer:

This paper briefly describes some markers around MAOA: http://www.biomedcentral.com/1471-2156/6/46

You have SNP states at these MAOA markers described in the paper: rs3788862, rs6323, rs979605. Looking at Figure 1, right side:

marker    you   A1 A2 A3 A4
rs3788862 A/T   C  T  T  C
rs6323    G/C   A  C  A  C
rs979605  A/T   C  T  C  T
            ^      ^

So it looks to me like you have type A2 -- or at least, you share these SNPs with the A2 set of this sample of Swedish individuals. The chance of coming to this configuration by chance is on the order of 1/64 (not quite, since the sites aren't independent). And: "Only two common haplotype variants of the MAOA locus were found among individuals of northern European ancestry."

Trait association: "Two MAOA haplotypes, A1 and A3, both sharing identical alleles at the three first haplotype positions (CCA-) (Figure 1), were associated with a significant decrease in trbc-MAO activity" You are A2; so I presume you have higher trbc-MAO activity. Skimming the PNAS paper, I see that "individuals with the low activity form of MAOA proved more likely to administer hot sauce to their opponent." So I conclude that if you and Attila the Hun were in a hot-sauce-administering contest, you would lose.

My friends are clever. Until someone shows me a study involving more than 573 Swedes, I've got my answer. Of couse, that's a mark of decent scientific thinking: I've found an acceptable answer based on the available information. I also have a decent grasp on where I might be wrong, and I retain a fair degree of curiosity about what else might be down this superficially simple rat-hole.

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