NCIt definition : 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.;
Alternative definition : NCI-GLOSS: 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.;
NCIt note : Two or more genes are said to be alleles if they occupy the same DNA sequence at a
locus on homologous chromosomes.;