bcftools merge does not work

[sjellerstrand]

Hej! I have found a potential bug in the develomental version. I get an error message when trying to merge several vcf files with bcftools merge. I have tried the the latest source code commit b7b2a32 for the following code. However, version 1.14, 1.16 and 1.17 works fine.

Command:

merge_files=$(echo ./Rasolark_2021_CADDXX010000136.1_HETGAM_95694_hetsex.vcf.gz ./Rasolark_2021_CADDXX010000136.1_HETGAM_TT95866_hetsex.vcf.gz)

bcftools merge $merge_files | bgzip -c > output.vcf.gz

The vcf file is not complete. It stops abruptly and has the following message at the end of the file:

[W::vcf_parse_info] INFO 'C' is not defined in the header, assuming Type=String
[E::bcf_write] Broken VCF record, the number of columns at CADDXX010000136.1:99689 does not match the number of samples (0 vs 2)
[main_vcfview] Error: cannot write to (null)

There is no INFO field called "C". What I do have is:

##INFO=<ID=AC,Number=A,Type=Integer,Description="Total number of alternate alleles in called genotypes">
##INFO=<ID=AF,Number=A,Type=Float,Description="Estimated allele frequency in the range (0,1]">
##INFO=<ID=NS,Number=1,Type=Integer,Description="Number of samples with data">
##INFO=<ID=AN,Number=1,Type=Integer,Description="Total number of alleles in called genotypes">

The site in the individual vcf files look like this:

# Rasolark_2021_CADDXX010000136.1_HETGAM_95694_hetsex.vcf.gz
CADDXX010000136.1       99824   .       TA      T       0       .       AC=1;AF=1;AN=1;CM=0.091753;NS=18        GT      1

#Rasolark_2021_CADDXX010000136.1_HETGAM_TT95866_hetsex.vcf.gz
CADDXX010000136.1       99824   .       TA      T       0       .       AC=1;AF=1;AN=1;CM=0.091753;NS=18        GT      1

However, the problem does not seem to be that site in particular. The site changes depending on if I run more/other samples. For example if I merge 4 other samples the site 99824 is processed and the file instead ends at site 100730 with the message:

[E::bcf_write] Broken VCF record, the number of columns at CADDXX010000136.1:100730 does not match the number of samples (0 vs 4)
[main_vcfview] Error: cannot write to (null)

And if I merge all my 9 files I get the following message:

[E::vcf_parse_format] FORMAT column with no sample columns starting at CADDXX010000136.1:100636
Error: VCF parse error

Neither is there any obvious issue with this site in any of theindividual files:

#Rasolark_2021_CADDXX010000136.1_HETGAM_95694_hetsex.vcf.gz
CADDXX010000136.1       100636  .       C       G       0       .       AC=1;AF=0.25;AN=1;CM=0.092565;NS=18     GT      1
#Rasolark_2021_CADDXX010000136.1_HETGAM_TT95866_hetsex.vcf.gz
CADDXX010000136.1       100636  .       C       G       0       .       AC=1;AF=0.25;AN=1;CM=0.092565;NS=18     GT      1
#Rasolark_2021_CADDXX010000136.1_HETGAM_TT95867_hetsex.vcf.gz
CADDXX010000136.1       100636  .       C       G       0       .       AC=1;AF=0.25;AN=1;CM=0.092565;NS=18     GT      1
#Rasolark_2021_CADDXX010000136.1_HETGAM_TT95871_hetsex.vcf.gz
CADDXX010000136.1       100636  .       C       G       0       .       AC=1;AF=0.25;AN=1;CM=0.092565;NS=18     GT      1
#Rasolark_2021_CADDXX010000136.1_HETGAM_TT95879_hetsex.vcf.gz
CADDXX010000136.1       100636  .       C       G       0       .       AC=1;AF=0.25;AN=1;CM=0.092565;NS=18     GT      1
#Rasolark_2021_CADDXX010000136.1_HETGAM_TT95881_hetsex.vcf.gz
CADDXX010000136.1       100636  .       C       G       0       .       AC=1;AF=0.25;AN=1;CM=0.092565;NS=18     GT      1
#Rasolark_2021_CADDXX010000136.1_HETGAM_TT95884_hetsex.vcf.gz
CADDXX010000136.1       100636  .       C       G       0       .       AC=1;AF=0.25;AN=1;CM=0.092565;NS=18     GT      1
#Rasolark_2021_CADDXX010000136.1_HETGAM_TT95887_hetsex.vcf.gz
CADDXX010000136.1       100636  .       C       G       0       .       AC=1;AF=0.25;AN=1;CM=0.092565;NS=18     GT      1
#Rasolark_2021_CADDXX010000136.1_HETGAM_TT95888_hetsex.vcf.gz
CADDXX010000136.1       100636  .       C       G       0       .       AC=1;AF=0.25;AN=1;CM=0.092565;NS=18     GT      1

Both cases are fixed for the alternate allele, but other site like it are being processed without any issue.

Again, there is none of these problems in previous versions.