Please can you clarify something for me regarding dbSNP. I know dbSNP stores lots of different types of variations but lets just use SNPs for simplicity. How can a SNP map to multiple different genomic locations? I thought a SNP was defined by its flanking sequence so if a SNP maps to multiple genomic locations it means the the entire flanking sequence of the SNP is repeated in multiple genomic locations so 'they' don't know which location it maps to. Is that correct?
Am i also right in noticing that in the latest release of dbSNP, SNPs that used to be classed mapping to multiple genomic locations seemed to have been merged ito new rs ids and now classed as not mapping to a particular assembly. I don't know if this is a new trend or just a coincidence in the records i was looking at.