• Mutually exclusive alternative forms of the same gene occupying the same locus on homologous chromosomes, differing in nucleotide sequence and governing the same biochemical and developmental process.
  NCI Thesaurus
  U.S. National Cancer Institute, 2021
• One of a series of possible alternative forms of a given gene, differing in DNA sequence, and affecting the functioning of a single product.
  CRISP Thesaurus
  National Institutes of Health, 2006
• One of two or more DNA sequences occurring at a particular gene locus. Typically one allele (normal DNA sequence) is common, and other alleles (mutations) are rare.
  NCI Dictionary of Cancer Terms
  U.S. National Cancer Institute, 2021
• One of two or more versions of a gene. Different alleles produce variations in inherited characteristics, such as eye color.
  Harvard Dictionary of Health Terms
  Harvard Medical Publishing, 2011
• The determination of which version of the gene is on each chromosome.
  CDISC Terminology
  Clinical Data Interchange Standards Consortium (CDISC), 2021
• Variant forms of the same gene, occupying the same locus on homologous CHROMOSOMES, and governing the variants in production of the same gene product.
  NLM Medical Subject Headings
  U.S. National Library of Medicine, 2021
• Allele, any one of two or more genes that may occur alternatively at a given site (locus) on a chromosome. Alleles may occur in pairs, or there may be multiple alleles affecting the expression (phenotype) of a particular trait. The combination of alleles that an organism carries constitutes its...
  Encyclopedia Britannica
  Encyclopedia Britannica, Inc., 2020