Genotype: The genotype of this variant call. Each value represents either the value of the referenceBases field or a 1-based index into alternateBases. If a variant had a referenceBases value of T and an alternateBases value of ["A", "C"], and the genotype was [2, 1], that would mean the call represented the heterozygous value CA for this variant. If the genotype was instead [0, 1], the represented value would be TA. Ordering of the genotype values is important if the phaseset is present. If a genotype is not called (that is, a . is present in the GT string) -1 is returned.