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Subject: Re: [DNA] FW: Family Tree DNA 59 Marker Update - from FTDNA
Date: Sun, 21 May 2006 20:08:15 +0100
Nora
the paper by Kayser et al
http://www.journals.uchicago.edu/AJHG/journal/issues/v74n6/41028/brief/41028
.abstract.html
which discovered most of the newest markers, found 475, of which 45 were
already known.
Of the remaining 430:
- 149 could not be researched further because suitable primers could not be
identified
- 115 were detectable in female as well as male DNA (so are not unique to
the Y chromosome)
- 27 did not show any variation in samples representing 8 different
haplogroups.
leaving 139 which could be analysed fully by the research team.
The study did not search for any new dinucleotide markers i.e. where the
repeat is made up of just two bases, like YCAii and DYS413. There are
probably hundreds of these but they tend to be difficult to analyse in
poor-quality DNA samples (the research team's interests include forensic
uses of DNA).
The study also ignored any STRs where the repeat length in the HUGO
reference sequence was less than 8, as there was a likelihood that these
would not be very variable.
To summarise
- there are just over 200 male specific STRs for which tests have been
designed and published
- there are over 100 which are not Y-specific - it might be interesting to
see if any of these are on the X chromosome and whether they are affected by
X-Y crossovers; also there may be some where the Y and non-Y copies have
non-overlapping ranges of alleles and so the Y allele could almost always be
distinguished
- there are over 100 which although not testable using current STR
technologies might be capable of being tested some time in the future (e.g.
by full sequencing)
- there are an unknown number (possibly quite large) of dinucleotide STRs
which may or may not be useful for genealogical research (DYS725 is one of
these)
- there are an unknown number (probably fairly small) of STRs which by
chance are shorter in the reference sequence than in human Y chromosomes
generally, or which are short but nevertheless show some variation between
different haplogroups
- in total perhaps 600 locations on the Y chromosome which could be regarded
as STR markers.
Gareth
----- Original Message -----
From: <>
To: <>
Sent: Sunday, May 21, 2006 3:35 PM
Subject: RE: [DNA] FW: Family Tree DNA 59 Marker Update - from FTDNA
>
> John,
>
> Does anyone know how many markers there actually are?
>
> Thanks.
>
> Nora
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