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Archiver > GENEALOGY-DNA > 2005-03 > 1111364174


From: "Paul Drake" <>
Subject: Re: [DNA] Halotype Analysis
Date: Sun, 20 Mar 2005 18:16:14 -0600
References: <032020051902.23294.423DC8D60007CCD200005AFE2207003201050B989A0E00@comcast.net> <003501c52d8c$2ad4aee0$eb409145@Ken1> <061401c52d8d$62366da0$6400a8c0@oemcomputer> <004b01c52d91$29f24be0$eb409145@Ken1>


Great explanation; the "catcatcat" analogy helped MUCH. Thanks so much, Ken.
----- Original Message -----
From: Ken Nordtvedt
To:
Sent: Sunday, March 20, 2005 3:09 PM
Subject: Re: [DNA] Halotype Analysis


Paul, I'll take a first crack. In most of the Y chromosome which does not
mix gene contributions from father and mother each generation, but which is
instead inherited father/son generation after generation, there are a number
of places where the genetic letters stutter and repeat themselves over and
over in some pattern. Like "catcatcatcatcat" would be a 5 time repeat of
the letters "cat"

These stuttering regions mutate at a substantially higher rate than other
kinds of mutations. The copying machine that reproduces the chromosome
seems to get lost sometimes when trying to "read" such regions. You might
do the same trying to tell me how many "cat" repeats I typed above. You
have to look carefully. When a mutation occurs the repeat number has
changed; most often but not always by a single repeat "up" or "down".

So our individual haplotypes are a collection of the number of repeats at a
designated number of places in the y chromosome. Those sets of numbers are
stable enough to look back through the male line ancestry, but they are not
so stable that the numbers don't start to diverge from each other the
further back the common male ancestor.

Right now some people know up to about 43 of their repeat numbers. Two
years ago they had had fewer measured. Next year more of these repeat areas
(STRs) may be commerically measurable. So it is most accurate to say we
right now can see what part of our haplotype is and compare it with that
same part of other peoples' haplotype. It has been estimated that
ultimately a male may have a couple hundred useful repeat numbers in his
"full" haplotype to be measured?

100,000 years ago, plus or minus a decent uncertainty, perhaps only a very
small number of males with just a small number of haplotypes left Africa,
and their descendants today populate the rest of the world --- Europe, Asia,
Australia, Americas. All haplotypes of these descendants today can be
considered to be derived from the small number of founder haplotypes through
a surprisingly small number of repeat number mutations.

My haplotype 15, 22, 13, 15, ..... at a designated set of places in the y
chromosome is a final product of some founding haplotype 100,000 years ago
and then the mutations that happened to have occured in the 3000 to 4000
generations which have gone by in between. Very roughly, if 1/300 is an
average mutation rate per generation per stuttering site, there have been
about 400 up or down, random mutational changes in the repeat numbers of my
43 number haplotype since the "Out of Africa" founding.

Ken
----- Original Message -----
From: "Paul Drake" <>
To: <>
Sent: Sunday, March 20, 2005 1:42 PM
Subject: [DNA] Halotype Analysis


>
> Anyone out there have a short explanation of the term "haplotype"
written for an experienced genealogist - ME - who knows ZIP about that term
and how it relates to a classical study of descendancy. The exchanges I
have seen on this fine web site are over my head, and I susupect I am not
alone. Why not occasionally include some explanations for us "newbies" ??
Thanks. Paul
>
>
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