DNA allele maps?

A friend gave me a coupon for a cheap DNA test, so I did it. But the company only gives the names of various gene loci and the number of the allele, with no real key to ferreting out the meaning. Where can I go to find this out?

For example, they give a result as D16S539: 8, 9. If I understand correctly, that means that my cells contain two alleles of D16S539, #8 from dad and #9 from mom or vice versa. Now, for all I know, 99% of humans bear one of these two alleles, and therefore it’s meaningless. Or perhaps #8 is strongly concentrated among Egyptians, with less and less frequency in concentric circles going out.

What I’d love is a nice map showing frequencies (like this), but really any source of factual information would be nice.

The results they gave just listed the top 10 countries whose populations are a match, by some methodology known only to them, and my results were in three areas: Middle Eastern countries, Latin countries, and Ireland. Sort of interesting, and slightly surprising.

I believe the “number” (8 or 9) indicates the relative length between two “cut points”.

DNA is treated with certain chemicals that will cut it where a certain combination of DNA is found. They then use the classic electrophoresis (?) technique, where the segments are attracted to the other side of the glass slide by an electric field. They lighter they are, the further they travel in the alloted time. For each test, you get a pair of lines at a certain distance from one edge of the slide. (Sort of like this: http://annals.org/data/Journals/AIM/19836/2FF3.jpeg )

This gives a set of numbers - so many units of DNA between A and B. Do this for enough DNA segments with different “cutting” chemicals, and you get the “fingerprint” look that typical DNA analysis yields. Knowing the relative distribution of these items in the general population, and you can give the odds that a sample is identical to another sample rather than a coincidence; and the odds that two samples indicate what degree of “related”. The major use is to prove paternity or relatedness. A and B get the same test, and based on the results, see if they have 50%, 25% etc. in common.

If you want to be tested for Huntingdons, Tay-Sachs or other genetic diseases - that’s a different DNA test.

The map you link to is for UEP’s (SNP’s) on the Y-chromosome, whereas your test was for STR’s on autosomes – there are many important differences between these types of allele.

The main difference is that UEP’s are inherited from Unique Event mutations which may have occurred a single time in all of human history, while STR counts often change between parent and child. On the map you link to, everyone with R1a Haplogroup descends patrilineally from the very same Central Asian male several thousands of years ago. Your count of 8 on D16S539 is much less meaningful as this count will fluctuate 8–>9–>10–>9–>10–>9–>8–> 7 etc. with passing generations all over the world. For this reason, a single STR count in isolation is almost meaningless: only an ensemble of several such markers gives meaning statistically.

Tests for UEP’s are much more expensive than tests for STR’s, I think. (An ensemble of STR’s on the Y-chromosome can be used, IIRC, to guess haplogroup, though strictly haplogroups are defined by UEP’s.)

Disclaimer: I am only an interested layman. I think the above discussion is nearly correct, but it comes with no waranty. :wink:

Thanks, this makes sense. (For what I paid, I wasn’t expecting much at all.)

The D165S539 loci is indeed a Short Tandem Repeat (STR) of AGAT nucleotides located at 16q24-qter (near the tip of the long arm of chromosome 16) and can indeed vary occasionally. But its not like there are changes every generation, just more frequently than a Y chromosome loci which does not undergo crossover and recombination in every generation.

The number of repeats varies considerably and is useful for paternity testing. Statistics on how frequently a particular number of repeats is found in a certain population group help determine the significance of any particular result. In one tested Brazilian population, 8 repeats (1.7%) was not as common as 9 repeats (15.1%), for example. In a studied southern Italian population 8 repeats (1.6%) and 9 repeats (13.3%) the stats were slightly different. In a Turkish population 8 repeats (1.4%) and 9 repeats (10.5%) again we see a difference in statistics.

I am not aware of any particular graphical map but the results the Op got were simply saying that those alleles are more common in certain middle eastern populations - but certainly not limited to those populations.