GENEALOGY-DNA-L ArchivesArchiver > GENEALOGY-DNA > 2005-10 > 1128700221
Subject: Re: [DNA] S21+ extends from 37 markers to 48 markers.
Date: Fri, 7 Oct 2005 16:50:21 +0100
a "point variation" is like a SNP i.e. a base change, insertion or deletion.
When it occurs in the section chosen to create the primers for the STR the
primers fail because they no longer match the target DNA closely enough.
DNAH may be using different primers because they have different
multiplexes - multiplexes are designed so that the possible lengths of
amplified sections for different STRs don't overlap (or those that do are
tagged with different colour dyes), so different combinations of STRs might
require the primers to be changed for some of them to ensure the
A point variation is potentially useful in multicopy markers - the DYS464X
test works for R1bs (most of them!) because there is a g to c mutation near
enough to some copies of the STR to allow different primer sets to lock on
to different copies.
DYS448 is located in the non-duplicated centre of palindrome P3 which has a
much larger non-duplicated section than the others (and fewer multicopy
----- Original Message -----
From: "Eldon Wade" <>
Sent: Friday, October 07, 2005 4:11 PM
Subject: [DNA] S21+ extends from 37 markers to 48 markers.
> I am one of the few on the list who have confessed to being derived at
> M269 and S21.
> I was tested at FTDNA for 37 markers and those test results have been
> for some time at Ysearch under ID SFVPS. In an effort to put as much info
> as possible before the list (so we can gain insight into S21) I ordered 23
> markers from DNAH. I of course got the 11 markers that RG and DNAH tests
> that FTDNA does not test. Those new results have been added to my results
> at Ysearch bringing me to 48 markers tested. I also retested 12 of my
> markers that were off the modal by some distance or I was particularly
> interested in. These included 385b, 390, 391, 439, 442, 447, 448, 449,
> 464a, 464d, and H4. After H4 was adjusted for the lab nomenclature
> difference, the results confirmed those I had previously received from
> - except for 448.
> DNAH had the following to say about DYS448: "We have repeated your test
> several times but were unable to get a value for DYS448. It is likely
> a point variation within the region where the DYS448 primers usually lock
> is prohibiting them from doing so. Thus the allele is not being amplified
> and thus detected. You may expect this to be found in descendants also."
> FTDNA had reported my DYS448=15, which of course is rare, but I do have a
> 34/37 match and we do match at 448=15. To remedy this problem I ordered a
> DYS448 test from DNAF this morning.
> Could someone please direct me to where I can learn about "point
> in STRs?
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