sequence role reference allele Being a 'reference allele' is a role or status assigned in the context of a specific dataset or analysis. In human variation datasets, 'reference' status is typically assigned based on factors such as being the most common in a population, being an ancestral allele, or being indentified first as a prototypical example of some feature or gene. For example, 'reference alleles' in characterizing SNPs often represent the allele first characterized in a reference genome, or the most common allele in a population. In model organism datasets, 'reference' alleles are typically (but not always) the 'wild-type' variant at a given locus, representing a functional and unaltered version of the feature that is part of a defined genomic background, and against which natural or experimentally-induced alterations are compared. An allele whose sequence matches what is consdiered to be the reference sequence at that location in the genome. reference allele