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Archiver > GENEALOGY-DNA > 2003-05 > 1052182952


From: "Alastair Greenshields" <>
Subject: Re: [DNA] Public African Y-DNA Databases?
Date: Tue, 6 May 2003 02:02:32 +0100


Hello list,

Just following on from last week's question of accommodation of
AfricanAncestry.com data at Ybase (www.ybase.org). To re-cap, African
Ancestry results have just 8 STR markers, but do have the YAP marker
analysed.

I've now allowed a YAP marker entry on the submission and editing forms (the
YAP being a SNP marker useful for African ancestry). The default on the
forms is 'not tested', but you can choose from Positive or Negative (you
either have YAP or you don't!). When you view each individual record,
you'll only see the YAP result field if that person has actually been tested
(otherwise it is hidden from view).

I've also changed the haplotype searches and reduced the number of
searchable markers from 10 down to just 8. This is to encourage people with
less markers - which includes AfricanAncestry.com customers to both enter
AND search.

The Ybase stats have also been updated (you may have to 'refresh' your
browser (usually F5)). The last 'snapshot' was carried out 3 months ago and
the database has roughly doubled. However, there is little significant
difference. I've provided a link on the statistics page
(www.ybase.org/statistics.asp) to the old stats so those with a mathematical
bent can compare and contrast! :)

A couple of comments - the picture for DYS454 and DYS455 may be a little
misleading given that it is entirely possible that not every Relative
Genetics customer would have changed their values for these two markers
(more info at www.ybase.org/convert.asp#DYS454andDYS455) - however, the
stats for the records at Ybase show that the percentages of people having
the modal values for DYS454 and DYS455 (both 11), is up quite a bit - with
96% of people being DYS454 = 11.

The DYS464 (a-d) series is interesting in that the distribution and
percentages of 'a' is similar to 'b', and also 'c' is similar to 'd'. I'd
not noticed this before, but it may give a speculative hint on how the
regions were split over time.

For a bit of background info, the DYS464 marker is 'duplicated' i.e. the
reaction primers amplify MORE THAN ONE region of DNA (usually primers only
amplify a single region). In the case of DYS464, 4 regions are amplified in
one reaction (occasionally more than 4), although each region is quite far
apart from each other in terms of base-pair distance along the Y-chromosome.

Comparing duplicated markers where the modal values are similar to each
other can be a little problematic. There was some debate on how to compare
two individuals on the DYS464 markers last week - infinite alleles vs.
stepwise models - although I think the jury is still out.

Anyway, here's hoping some more African results can now be easily entered.

Kind Regards,
Alastair




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