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Subject: Re: [DNA] PubMed abstract: DAZ genes on the Y chromosome
Date: Sun, 18 Jun 2006 16:39:18 +0100
From the abstract this paper looks like a development of previous research
into locations which have SNP-like variations between different arms of the
P1 and P2 palindromes, just like the one underlying the DYS464X test.
Interesting that both this research team and its main competitor (David
Page's team at MIT) are moving from just studying infertility-linked
variations to the broader question of the structural evolution of the Y
chromosome which is much more relevant to us. It will be interesting to see
what are the correlations with the standard single-copy SNPs. The most
likely application to genealogy that I can see is where someone has a
different pattern of variations than what is "normal" for his haplogroup,
suggesting a recent recombinational change which should be shared by close
relatives. We have seen this with DYS464X where a family line in R1b1c has
cccc or ccgg instead of the usual cccg pattern.
Gareth
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Sent: Sunday, June 18, 2006 1:58 PM
Subject: [DNA] PubMed abstract: DAZ genes on the Y chromosome
> The multi-copy marker DYS464 is located in this region. From the abstract,
it
> sounds like they found SNPs helpful in distinguishing between duplicated
> copies, although they would not necessarily be applicable to our DYS464
riddles.
>
> =====
>
> Mol Hum Reprod. 2006 Jun 15; [Epub ahead of print]
>
> DAZ gene copies: evidence of Y chromosome evolution.
>
> Fernandes AT, Fernandes S, Goncalves R, Sa R, Costa P, Rosa A, Ferras C,
> Sousa M, Brehm A, Barros A.
>
> Laboratory of Human Genetics, University of Madeira, Funchal, Madeira.
>
> The DAZ gene, a contributing factor in infertility, lies on the human Y
> chromosome's AZFc region, whose deletion is a common cause of
spermatogenic
> failure. Y chromosome binary polymorphisms on the non-recombining Y (NRY)
region,
> believed to be a single occurrence on an evolutionary scale, were typed in
a
> sample of fertile and infertile men with known DAZ backgrounds. The Y
> single-nucleotide polymorphisms (Y-SNPs) with low mutation rates are
currently well
> characterized and permit the construction of a unique phylogeny of
haplogroups. DAZ
> haplotypes were defined using single-nucleotide variant (SNV)/sequence
> tagged-site (STS) markers to distinguish between the four copies of the
gene. The
> variation of 10 Y chromosome short tandem repeat (STRs) was used to
determine the
> coalescence age of DAZ haplotypes in a comparable time frame similar to
that
> of SNP haplo-groups. An association between DAZ haplotypes and Y
chromosome
> haplogroups was found, and our data show that the DAZ gene is not under
> selective constraints and its evolution depends only on the mutation rate.
The same
> variants were common to fertile and infertile men, although partial DAZ
> deletions occurred only in infertile men, suggesting that those should
only be used as
> a tool for infertility diagnosis when analysed in combination with
haplogroup
> determinations.
>
> PMID: 16777954 [PubMed - as supplied by publisher]
>
> =====
>
> Ann Turner
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