I am a clinician, and have no particular expertise in genomics. I'm confused by much of what I see on dbSNP. Any help would be greatly appreciated! Thank you in advance.

I need some help understanding HGVS Names!

I see SNP's referred to with conventions like **A66G** for MTRR ([rs1801394][1]) and **A1298C** for MTHFR ([rs1801131][2]).

When I look under **HGVS names** for rs1801394 I see: NM_002454.2:c.66A>G, which l assume equals "A66G", but there are many other "names" there. What are these names? Are they all equivalent?

When I look under **HGVS names** for rs1801131 I do not see anything resembling "A1298C". Does this mean I have the wrong rs# for this SNP?

According to [SNPedia][3], it's the correct rs#: "rs1801131 is a SNP in the MTHFR gene, representing an A>C mutation at mRNA position 1298".

 [1]: http://www.ncbi.nlm.nih.gov/projects/SNP/snp_ref.cgi?rs=1801394
 [2]: http://www.ncbi.nlm.nih.gov/projects/SNP/snp_ref.cgi?rs=1801131
 [3]: http://www.snpedia.com/index.php/Rs1801131
I'll try to explain briefly, but it's a lot and it's wonderful - one of the rare parts where we have great standards.Check it out: http://www.hgvs.org/mutnomen/

The usual format is:

    <REFERENCE_SEQUENCE_ID>:<SEQUENCE_TYPE>.<POSITION><CHANGE>

`NM_002454.2:c.66A>G`is a cDNA change of Adenine to Guanine at position `66` in the cDNA ref sequence `NM_002454` version 2.

`A66G` most commonly refers an amino acid change of Alanine to Glycine in some protein with some identifier (should ideally be `NP_xxxxxxx:p.A66G`). In your case though, I think you might be referring to a `66A>G` nucleotide change as `A66G`, which is wrong.

Ref sequences can be `g.` (genomic), `c.` (cDNA), `r.` (RNA) or `p.` (protein)

Changes can be single amino acid variants (`p.Ala66Gly`) single nucleotide variants (`A>G`), deletions(`c.10delA`), insertions (`c.10_11insT`), duplications (`c.10dupA`), indels(`c.10_11delACinsTGA`) etc.

It is so well standardized that programs can parse and pick individual components for us to use.