Create a normalized variantkey.

Create a normalized variantkey.

NormalizedVariantKey(chrom, pos, posindex, ref, alt,
  mf = vk.env$genoref_$MF)

Arguments

chrom	Chromosome encoded number.
pos	Position. The reference position.
posindex	Position index: 0 for 0-based, 1 for 1-based.
ref	Reference allele. String containing a sequence of nucleotide letters.
alt	Alternate non-reference allele string.
mf	Memory-mapped file object as retured by MmapGenorefFile.