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Archiver > GENEALOGY-DNA > 2005-10 > 1128700912


From: "Ken Nordtvedt" <>
Subject: Re: [DNA] S21+ extends from 37 markers to 48 markers.
Date: Fri, 7 Oct 2005 10:01:52 -0600
References: <200510071511.j97FBVb6011524@ms-smtp-02.tampabay.rr.com> <006b01c5cb56$d9a28560$2497893e@Masterbedroom>


So I learn that there are many different primers that generally can do the
job of bracketing and isolating a STR for its measurement. Question: can I
expect the different labs to generally have made their own version of the
primer(s) which will differ from the primer(s) of other labs? Or is the use
of different primers the exception rather than the rule?

And is there a similar issue concerning the primers which isolate a region
where SNPs are located? Will one lab usually be using different primers
than another?

Ken
----- Original Message -----
From: <>
To: <>
Sent: Friday, October 07, 2005 9:50 AM
Subject: Re: [DNA] S21+ extends from 37 markers to 48 markers.


> Eldon
>
> 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
> multiplexing works.
>
> 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
> STRs).
>
> Gareth
>
>
> ----- Original Message -----
> From: "Eldon Wade" <>
> To: <>
> 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
> both
>> M269 and S21.
>> I was tested at FTDNA for 37 markers and those test results have been
> posted
>> 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,
> 458,
>> 464a, 464d, and H4. After H4 was adjusted for the lab nomenclature
>> difference, the results confirmed those I had previously received from
> FTDNA
>> - 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
> that
>> a point variation within the region where the DYS448 primers usually lock
> on
>> 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
> variation"
>> in STRs?
>>
>> Eldon
>
>
>
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