Fw: SNPs

Deanne Bell dbell at qnis.net
Tue Jan 23 14:27:27 EST 2001


Hi all
This is a rookie question but I'll ask anyway
Can you please define SNPs?
D. Bell

----------
> From: Dr N.I. Leaves <nleaves at hgmp.mrc.ac.uk>
> To: methods at hgmp.mrc.ac.uk
> Subject: Re: SNPs
> Date: Tuesday, January 23, 2001 4:44 AM
> 
> Hi Raja, I'm not sure about plant systems and SNPs.
> 
> In human populations SNPs have advantages and disadvantages in
> genetic mapping studies.
> 
> In the last ten years or so di-, tri-, and tetranucleotide
> repeat microsatellites have been widely used in mapping. These are
> extremely informative in linkage studies where the large number of
alleles
> are exploited. However, their mutability makes them less useful in
studies
> of linkage disequilibrium where association between marker and disease
> mutation might have drifted. In contrast SNPs are much more stable in
> populations and are likely to be useful in studies of linkage
> disequilibrium, especially if used in haplotypes. However, their
> informativity is much lower when considered as single markers. In
> humansib-pair studies, I think genome wide estimates of 8 or so SNPs to
> replace a single microsatellite have been made.
> 
> SNPs occur at a greater frequency (>1 SNP/kb) than microsatellites so
> there are plenty out there. Typing SNPs is however generally problematic
> in mapping studies of outbred populations where large numbers of SNPs 
> (many 1000s) typed on large numbers of DNAs would be needed in a genome
> wide application. Currently, there are many commercial organisations
> fighting to prove their technology is capable of large scale SNP genetic
> studies.
> 
> I hope these ramblings are of some help
> 
> Best wishes
> 
> Nick Leaves
> 
> (end)
> **************************************************
> Dr N I Leaves
> Mouse Sequencing - Production Manager
> MRC HGMP Resource Centre
> Hinxton
> Cambridge CB10 1SB
> tel: 01223 494557 (office) or 01223 494541 (lab)
> email: nleaves at hgmp.mrc.ac.uk
> **************************************************
> 
> 
> **************************************************
> 
> On Mon, 22 Jan 2001, Dr Raja Kota wrote:
> 
> > Dear Netters,
> > 
> > So far what I have read about SNPs, they are generally biallelic in a
given
> > population.  I am not sure whether this hold true in plant systems as
well.
> > in any case, is it advantageous in mapping studies to employ biallelic
> > systems???.  If so, why?.
> > 
> > Thanks in advance,
> > 
> > Raj
> > 
> > 
> > 
> 
> 


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