The start position of SV and CNVs at the gnomAD browser might be the preceding position

Structural Variation
1

Hi gnomAD team,
The VCF specification (section 1.6.1) denotes the following for the position (POS) of structural variants (e.g. <DEL>) in the VCF file :

REF — reference base(s): (…) If any of the ALT alleles is a symbolic allele (an angle-bracketed ID String ) then the padding base is required and POS denotes the coordinate of the base preceding the polymorphism.

However I noticed that exactly the same position from the VCF file (that is the preceding base) is reported in the gnomAD browser as the position of the variant. For instance,

VCF:

chr1    11000   gnomAD-SV_v3_DUP_chr1_7d73682f  N       <DUP>   999     PASS    ALGORITHMS=depth;CHR2=chr1;END=51000;...

Webportal: DUP_CHR1_7D73682F | gnomAD SVs v4.1.0 | gnomAD (broadinstitute.org) | 11000 - 51000

I wonder if the start position in the gnomAD browser should increase 1 bp to reflect the start position of the variant. Thank you very much

Best,
Javier

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