Counts and frequency of alleles in called genotypes
INFO=<ID=AF,Number=A,Type=Float,Description="Allele Frequency, for each ALT allele, in the same order as listed">
INFO=<ID=AC,Number=A,Type=Integer,Description="Allele count in genotypes, for each ALT allele, in the same order as listed">
INFO=<ID=AN,Number=1,Type=Integer,Description="Total number of alleles in called genotypes">
This annotation outputs the following:
AC=1;AF=0.500;AN=2
This set of annotations, relating to a heterozygous call(0/1) means there is 1 alternate allele in the genotype. The corresponding allele frequency is 0.5 because there is 1 alternate allele and 1 reference allele in the genotype. The total number of alleles in the genotype should be equivalent to the ploidy of the sample.