What is the difference between different releases of dbSNP?

Question

[Morgan]

My question is really as simple as the title, but in particular, I'm interested in the following dimensions:

1. Is dbSNP backwards compatible? Are new releases always supersets of old releases? Are existing records updated with subsequent releases?
2. If I annotate two sets of variants (in VCF) with different dbSNP versions, can I compare the two or do they have to be annotated with the same version of dbSNP in order to be meaningful?

A little background: we have existing variant calling pipelines for genomic and transcriptomic data using dbSNP releases as far back as 132 and I'm trying to standardize and update them.

Thanks in advance.

Answer 1

[Pierre Lindenbaum]

1. No, some records are merged: http://www.ncbi.nlm.nih.gov/sites/books/NBK44468/ e.g: http://www.ncbi.nlm.nih.gov/snp/?term=56500751
2. Same as 1) if you find a #rs at a given CHROM/POS, it might not be the same #rs-id in the new version of dbsnp.

[Morgan]

Follow up question: Are the new releases better enough to consider reannotating everything?

I guess this is a silly question since why would there be new releases if they weren't better!