Hello,

The refFlat file would be an appropriate place to search. Make sure that it is 
downloaded from the hg18 (not hg19) ftp location.

Only SNPs from the reference genomic sequence should be mapped. The RefSeq 
annotation is based on this assembly. Coordinates from other assemblies, such 
as the alternate Celera assembly, will not align correctly.

If there is not match, then the SNPs have no overlap. You may consider other 
Gene tracks. Open the browser and examine the tracks in the Gene and Gene 
Predictions group. UCSC Genes would be the best place to start - it contains 
RefSeq plus other input sources. The track description provides details about 
the methods.

Some coordinate help:
http://genomewiki.ucsc.edu/index.php/Coordinate_Transforms

And file format help:
http://genome.ucsc.edu/FAQ/FAQformat.html

Jennifer


------------------------------------------------ 
Jennifer Jackson 
UCSC Genome Bioinformatics Group 

----- [email protected] wrote:

> From: [email protected]
> To: [email protected]
> Cc: [email protected]
> Sent: Friday, February 5, 2010 1:43:20 AM GMT -08:00 US/Canada Pacific
> Subject: Query about hg18 genomic coordinates
>
> Dear Jennifer,
> 
> We have a list of SNPs with genomic co-ordinates (both from ncbi,
> celera &
> ref assemblies) that we would like to get corresponding gene
> annotations
> for. We don't have the flanking sequence, gene name, ID, gene length,
> CDS
> or any other information. Currently, we are using build hg18 (ncbi
> 36.1).
> What file should we search against to look for gene annotations? We
> understand the genomic co-ordinates do change with different build
> numbers
> and hence we would like to search in build 18 only. When we searched
> against the genomic regions between column 5&6 in the the refflat.txt
> file, for certain SNPs (especially those from celera & ref
> assemblies)
> don't match to anything in the refflat.txt file. Any suggestions would
> be
> useful.
> 
> Thank you.
> 
> Rakhi
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