Where is the person's "unique id" in the genome?



R

Ramon F Herrera

Guest
I was watching the excellent documental "DNA" in PBS, and they mentioned that there is a section in
some chromosome which is unique for every individual. This is the section used in identifying
criminals, etc.

Where exactly is this section located? Where can I read more about it?

TIA,

-Ramon
 
G

Guy Hoelzer

Guest
in article [email protected], Ramon F Herrera at
[email protected] wrote on 1/27/04 10:58 AM:

> I was watching the excellent documental "DNA" in PBS, and they mentioned that there is a section
> in some chromosome which is unique for every individual. This is the section used in identifying
> criminals, etc.
>
> Where exactly is this section located? Where can I read more about it?

I think you misunderstood. There is no particular section of DNA designed to mark individual
identities. There are, however, many (hundreds of thousands) of places in the genome that exhibit
much higher mutation rates and current variation than other regions of the genome, and a small set
of these regions (dozens of them) is commonly used to identify criminals, etc.. These hypervariable
regions are called by many names, the most common of which is "microsatellites," which are
characterized by a series of short (about 2-8 bases) tandemly repeated sequences. You find
microsatellites everywhere you look in the genome.

Guy
 
J

J Moore

Guest
I was looking for a decent link to get some basics for you, but it turns out
to be difficult because of having to wade through a lot of ads for DNA ID
kits. I did find this one which is informative and straightforward.
http://www.kgl900.com/html/body_dna.htm

The upshot is that they don't check one area, and that to be absolutely accurate you'd want to check
the whole genome, which is of course not practical now. So they check a number of areas where you
usually see the most differences between individuals. Finding that just one of these matches doesn't
necessarily make for a correct ID, but as you find more areas matching the odds go up that you're
seeing a correct match. This is a bit like saying we've got a guy named Herrera, so is that you?
Maybe, but there's a lot of people with that name. So they look for a first name, and an initial,
and an address, and maybe an age, and height. Now if all those match, it's probably you. The odds
are that there isn't somone else at that address with the same name, age, height, etc., and the odds
get better the more things you check and find matches for. So that's what they're doing with DNA
identification.

Jim

Ramon F Herrera <[email protected]> wrote in message news:[email protected]...
> I was watching the excellent documental "DNA" in PBS, and they mentioned that there is a section
> in some chromosome which is unique for every individual. This is the section used in identifying
> criminals, etc.
>
> Where exactly is this section located? Where can I read more about it?
>
> TIA,
>
> -Ramon
 
M

Morten Eriksen

Guest
[email protected] (Ramon F Herrera) writes:

> I was watching the excellent documental "DNA" in PBS, and they mentioned that there is a section
> in some chromosome which is unique for every individual. This is the section used in identifying
> criminals, etc.
>
> Where exactly is this section located? Where can I read more about it?

The forensic use of DNA is discussed at some length in Richard Dawkins's _Unweaving the Rainbow_,
chapter 5, "Barcodes at the bar".

If I remember correctly, the most common thing to do is to check the number of tandem repeats in a
particular piece of non-coding / junk DNA. Tandem repeat sequences in non-coding DNA typically (?)
varies a lot in a population, it will likely differ on the maternal versus the paternal chromosome,
and is easy to measure.

Morten
--
Ees a sad an' beautiful world
 
D

David Judah Lay

Guest
[email protected] (Ramon F Herrera) wrote in message news:<[email protected]>...
> I was watching the excellent documental "DNA" in PBS, and they mentioned that there is a section
> in some chromosome which is unique for every individual. This is the section used in identifying
> criminals, etc.
>
> Where exactly is this section located? Where can I read more about it?
>
> TIA,
>
> -Ramon

Are you referring to the Mitochondra DNA?