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From: (David Faux)
Subject: Re: [DNA] Costs, Multiplexing and Related Issues
Date: Fri, 22 Jul 2005 22:44:56 +0000


Bob:

I already cited two references that show that at least to this point, multiplexing has not worked in population genetics studies since it seems to have difficulties with certain (but not all markers).

I already gave P25 and M17 as examples. The studies noted are Brion et al., "A collaborative study of the EDNAP group regarding Y-chromosome binary polymorphism analysis", Forensic Science International, 2004 (I have the online version do do not have page numbers). Only two of six labs labs were able to find any M17 - 1 of 51 in Norway, and 3 of 129 in Innsbruck. The lab in Norway found only 4 of 51 R1b, Innusbruck found 1 R1b in a sample of 129 and apparently there is no R1b in Munster Germany where in other databases it predominates. In other words of the few markers they examined most labs were unable to multiplex P25 and M17.

The second study was Neiderstatter et al., "Separate analysis of DYS385a and b versus conventional typing: is there forensic evidence?", Int. J. Legal. Med., 2004, 119, 1-9 (this study also amplified M17F, M17 R, M35F, M35R, P25F, P25R, M213F, M213R. P25 was multiplexed. The study of Tyroleans in Austria found 42 P*(xR1b,R1a) and one R1b.

You may recall that David Wilson of the List followed up and the authors admitted that their results were in error - it is inconceivable that there would be one R1b in a sample of 113 Austrians (where R1b predominates).

We discussed this earlier in the year on the List, but I don't think that multiplexing was mentioned, however this was the technique employed. Clearly it has major problems for some important markers. Does it work any better today, or will we still get strange results? How can its use be justified in light of this rather dramatic evidence? Anyway, for now in our lab we will stick to what we know works until studies are published that are successfully multiplex P25 and M17 - and I really don't know how many other markers will fail since so few have been reported.

I trust that I have addressed your concern about references or citations.

David F.



-------------- Original message --------------

> David,
>
> The choice will clearly depend on the circumstances of each case.However, I am
> trying to get the facts straight. I can't take yours as unbiased opinions about
> a competitor's testing methodology. Does Consumer Reports use GM's opinions on
> Hondas?
>
> I simply asked you to back up your statements with a citation. Just a statement
> from an unbiased source would help. If what you say is true, I would like to
> know, so I can factor it into my analysis. I gave a citation for what I stated,
> so people can assess it for themselves. Do you expect us to accept your opinions
> about a competitor's test without question? Do you expect us to ignore John
> Butler?
>
> Bob Stafford

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