Allele

An allele, ; ; modern formation from Greek ἄλλος állos, "other"}}, or allelomorph, is a variant of the sequence of nucleotides at a particular location, or locus, on a DNA molecule.
Alleles can differ at a single position through single nucleotide polymorphisms (SNP), but they can also have insertions and deletions of up to several thousand base pairs.
Most alleles observed result in little or no change in the function of the gene product it codes for. However, sometimes different... meer