For example, some leopards have a mutation which causes black fur. So Black fur and normal fur colour (orange-white) are both alternate forms of the same gene, right? So does that mean that mutations cause alleles?



1 Answer 1


That's correct. Alleles are alternate forms of a gene that occur at the same locus and arise by mutation. Another example might be sickle cell anemia where a SNP (a single base change) is the cause of the disease.

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    $\begingroup$ Not correct. Alleles can be identical. They are just copies of the same gene. You get one copy from Mom, and the other from Dad. Alleles need not be alternate forms. Mutations cause variation. $\endgroup$
    – Karl Kjer
    Feb 10, 2018 at 4:00
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    $\begingroup$ @KarlKjer OED: "Allele: Each of two or more alternative forms of a gene that arise by mutation and which may be found in the same position on a homologous chromosome." Can you point to a source that unambiguously uses 'allele' in the sense that you are suggesting (i.e. as a synonym for 'copy')? $\endgroup$
    – Alan Boyd
    Feb 10, 2018 at 11:09

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