replace hardcoded index value with constant defined early in the file.
replace hardcoded index value with constant defined early in the file.

EichlerLab/pacbio_variant_caller,EichlerLab/pacbio_variant_caller,EichlerLab/pacbio_variant_caller,EichlerLab/pacbio_variant_caller,EichlerLab/pacbio_variant_caller