Any one of a series of two or more different genes that may occupy the same locus on a specific chromosome. As autosomal chromosomes are paired, each autosomal gene is represented twice in normal somatic cells. If the same allele occupies both units of the locus, the individual or cell is homozygous for this allele. If the alleles are different, the individual or cell is heterozygous for both alleles.
See: DNA markers
[G. allēlōn, reciprocally]
See Also: dominance of traits
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Examples: glitazone, GI cocktail, etc.