Question: I downloaded the SV from gnomad:

wget -O gnomad_v2_sv.sites.vcf.gz "https://storage.googleapis.com/gnomad-public/papers/2019-sv/gnomad_v2_sv.sites.vcf.gz"

wget -O gnomad_v2_sv.sites.vcf.gz.tbi "https://storage.googleapis.com/gnomad-public/papers/2019-sv/gnomad_v2_sv.sites.vcf.gz.tbi"

First, an observation. For BND, the END value is used in the gnomad browser as the 'END' position of the second junction:

e.g: https://gnomad.broadinstitute.org/variant/BND_1_13?dataset=gnomad_sv_r2 ; https://gnomad.broadinstitute.org/variant/BND_1_21?dataset=gnomad_sv_r2 ; https://gnomad.broadinstitute.org/variant/BND_1_31?dataset=gnomad_sv_r2

https://twitter.com/yokofakun/status/1143440104582733825

( I submitted an issue https://github.com/macarthur-lab/gnomad_browser/issues/139 )

Here is my problem: there is this variant:

$ bcftools view gnomad_v2_sv.sites.vcf.gz | grep gnomAD_v2_CTX_12_13 -m1
12	60718971	gnomAD_v2_CTX_12_13	N	999	PASS	END=57020218;SVTYPE=CTX;CHR2=13;SVLEN=-1;ALGORITHMS=manta;EVIDENCE=PE;CPX_TYPE=CTX_PP/QQ;PROTEIN_CODING__NEAREST_TSS=SLC16A7;PROTEIN_CODING__INTERGENIC;AN=21476;AC=1;AF=4.7e-05;N_BI_GENOS=10738;N_HOMREF=10737;N_HET=1;N_HOMALT=0;FREQ_HOMREF=0.999907;FREQ_HET=9.31272e-05;FREQ_HOMALT=0;AFR_AN=9480;AFR_AC=0;AFR_AF=0;AFR_N_BI_GENOS=4740;AFR_N_HOMREF=4740;AFR_N_HET=0;AFR_N_HOMALT=0;AFR_FREQ_HOMREF=1;AFR_FREQ_HET=0;AFR_FREQ_HOMALT=0;AMR_AN=1784;AMR_AC=1;AMR_AF=0.000561;AMR_N_BI_GENOS=892;AMR_N_HOMREF=891;AMR_N_HET=1;AMR_N_HOMALT=0;AMR_FREQ_HOMREF=0.998879;AMR_FREQ_HET=0.00112108;AMR_FREQ_HOMALT=0;EAS_AN=2226;EAS_AC=0;EAS_AF=0;EAS_N_BI_GENOS=1113;EAS_N_HOMREF=1113;EAS_N_HET=0;EAS_N_HOMALT=0;EAS_FREQ_HOMREF=1;EAS_FREQ_HET=0;EAS_FREQ_HOMALT=0;EUR_AN=7598;EUR_AC=0;EUR_AF=0;EUR_N_BI_GENOS=3799;EUR_N_HOMREF=3799;EUR_N_HET=0;EUR_N_HOMALT=0;EUR_FREQ_HOMREF=1;EUR_FREQ_HET=0;EUR_FREQ_HOMALT=0;OTH_AN=388;OTH_AC=0;OTH_AF=0;OTH_N_BI_GENOS=194;OTH_N_HOMREF=194;OTH_N_HET=0;OTH_N_HOMALT=0;OTH_FREQ_HOMREF=1;OTH_FREQ_HET=0;OTH_FREQ_HOMALT=0;POPMAX_AF=0.000561

1) The Broad uses **SVTYPE=CTX** : isn't it against the VCF spec ?

> Value should be one of DEL, INS, DUP, INV, CNV, BND.

2) The Broad uses INFO/**END** as the second locus of the translocation. here chr12->60718971 chr13/END=57020218 isn't it against the VCF spec ?

3) And eventually, why can't I find this variant with bcftools (1.9-94-g9589876) or tabix ??

$ bcftools view gnomad_v2_sv.sites.vcf.gz "12:60718970-60718972" | grep gnomAD_v2_CTX_12_13
$
$ tabix gnomad_v2_sv.sites.vcf.gz "12:60718970-60718972" | grep gnomAD_v2_CTX_12_13
$

Answer: 1) That says **should**, not **must**. To my reading, that means you can invent your own keywords as well, though it behooves you to describe them well. The text in the VCF 4.3 spec (which, once again, I recommend as being clearer and more detailed than the earlier documents) has

> The reserved values must be used for the types listed below:
>
> - DEL: Deletion relative to the reference
> - INS: Insertion of novel sequence relative to the reference
> - DUP: Region of elevated copy number relative to the reference
> - INV: Inversion of reference sequence
> - CNV: Copy number variable region (may be both deletion and duplication)
> - BND: Breakend

which to my mind still means you are free to invent your own keywords for other things. Apparently they would rather use their own CTX (*Reciprocal chromosomal translocation*) than the specification's admittedly cumbersome BND.

2) “The Broad uses INFO/**END** as the second locus of the translocation”, while the VCF specification describes it as

> End position (for use with symbolic alleles)

and further specifies it in §3 as

> For precise variants, END is POS + length of REF allele − 1, and the for imprecise variants the corresponding best estimate.

GnomAD's use of END with a different meaning is in direct contravention of the VCF specification.

3) Indexing VCF uses the CHROM and POS as the start of the interval in which the record lies, and uses a combination of REF length, ALT length, and INFO/END to determine the end of the interval. So gnomAD's abuse of END containing unrelated values leads to a broken index.

If you decompress *gnomad_v2_sv.sites.vcf.gz*, use `sed` or your text editor to change all the END= to a different identifier, and then `bgzip` and `bcftools index` it again, you will find that the index works as expected and this `12:60718970-60718972` query finds just that one variant record.

This indexing problem is a pretty good demonstration of why gnomAD should not be inventing its own meaning for INFO/END or other VCF-spec-prescribed tags!