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I'm in a fix.

Prepare yourself for a long read

We've just learned about minisatellites and microsatellites at class (okay, by "learned", I mean we were told their definitions and essentially nothing else... hardly surprising, since we aren't expected to know more than that at school).

Shortly afterwards, we touched on the topic of DNA profiling, and my textbook went on to state:

Minisatellites are hypervariable and are specific to each individual. This uniqueness is employed in DNA profiling.

Which would imply that the repetitive DNA fragments used in DNA profiling (VNTRs - Variable Number Tandem Repeats) are (only?) minisatellites.

Fine.


However, the Wikipedia pages on minisatellites and microsatellites (I linked both of them earlier on in this post) mention:

(Minisatellites and microsatellites)... together are classified as VNTR (variable number of tandem repeats) DNA. Confusingly, minisatellites are often referred to as VNTRs, and microsatellites are often referred to as short tandem repeats (STRs) or simple sequence repeats (SSRs).

If I interpreted this correctly, it's saying;

"Both minisatellites and microsatellites are classified as VNTRs. But when one normally talks about "VNTRs" he/she is referring to minisatellites. Microsatellites are, instead, commonly referred to as STRs/SSRs."

Okay, so far so good.

The Wikipedia page on microsatellites explicitly states that they (the microsatellites) are the ones you deal with in DNA profiling. However, the Wikipedia page on minisatellites carries no clear indication of their (minisatellites) use in DNA profiling.

Ugh.

And to compound my confusion, the Wikipedia page on DNA profiling states:

DNA profiling uses repetitive ("repeat") sequences that are highly variable,called variable number tandem repeats (VNTRs), in particular short tandem repeats (STRs), also known as microsatellites, and minisatellites.

Which suggests that both minisatellites and microsatellites are used in DNA profiling (as they're both VNTRs), but microsatellites are more relevant in this regard.


Summing up what I said:

  • My textbook says that DNA profiling makes use of VNTRs.

  • My textbook (and teacher) says DNA profiling makes use of only minisatellites.

  • Wikipedia says that VNTRs refer to both minisatellites and microsatellites.

  • Wikipedia says that VNTRs are typically mentioned in reference to minisatellites. Whereas microsatellites (which are strictly "VNTRs") are better known as STRs/SSRs.

  • Wikipedia says (explicitly) that microsatellites are used in DNA profiling. It doesn't mention minisatellites in this regard.

  • Wikipedia says that both minisatellites and microsatellites are used in DNA profiling, but minisatellites are use more often.

This inconsistency over the three Wikipedia articles I've linked is seriously annoying


My question(s),

1) I'm told that VNTRs are used in DNA profiling. Does this refer to both minisatellites and microsatellites...or just minisatellites?

2) If only one of them is used, why disregard the other? They're both (technically) VNTRs aren't they? So shouldn't either of them work just fine?

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    $\begingroup$ I have complained many times about too long questions in the past. It is good to see here a long question, which has good reasons to be long. Also, it is nice to see a long question with a pleasant format.+1 $\endgroup$ – Remi.b Oct 10 '17 at 14:34
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1) I'm told that VNTRs are used in DNA profiling. Does this refer to both minisatellites and microsatellites...or just minisatellites?

Actually, it refers mostly to STRs. I worked a bit in forensic genetics and we always published works using STRs markers (one example here, there are plenty in the literature).

In addition, I would not be surprised if current forensic identification used SNPs instead, e.g. as proposed in this paper

2) If only one of them is used, why disregard the other? They're both (technically) VNTRs aren't they? So shouldn't either of them work just fine?

I really don't know, but I am sure that it has to do with one of a) level of variation, i.e. if minisatellites have lower mutation rates and are less variable, then they also are less useful, b) ease of genotyping.

Browsing in the web I found this website from which I understand that the minisatellites were the first to be used to perform DNA profiling (using a method different from sequencing) and that "modern" DNA profiling is performed using STRs. However, I insist that modern DNA profiling should be better performed using SNPs.

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