The <i>a</i> for agouti locus in the mouse has over a dozen alleles. (Note: The locus name and symbol predate the guidelines and were retained for stability.) Here are a few to show how symbols are assigned to multiple alleles:<br><ul>
<li><i>A<sup>vy</sup>.</i> Viable yellow. Dominant to the normal allele. Homozygotes and heterozygotes are variable in color, ranging from clear yellow through yellow spotted to agouti.<br>
<li><i>A<sup>y</sup>.</i> Dominant yellow. Codominant to the normal allele. Homozygotes die at birth. Heterozygotes are yellow.<br>
<li><i>a<sup>+</sup>.</i> Wild type. The normal allele. The normal or agouti color.<br>
<li><i>a.</i> Nonagouti. Recessive to the normal allele. Homozygotes are black with a little yellow around the nipples and anus.<br>
<li><i>a<sup>e</sup>.</i> Extreme nonagouti. Recessive to the normal allele. Homozygotes are black, including around the nipples and anus.<br> </ul>
<li><i>A<sup>vy</sup>.</i> Viable yellow. Dominant to the normal allele. Homozygotes and heterozygotes are variable in color, ranging from clear yellow through yellow spotted to agouti.<br>
<li><i>A<sup>y</sup>.</i> Dominant yellow. Codominant to the normal allele. Homozygotes die at birth. Heterozygotes are yellow.<br>
<li><i>a<sup>+</sup>.</i> Wild type. The normal allele. The normal or agouti color.<br>
<li><i>a.</i> Nonagouti. Recessive to the normal allele. Homozygotes are black with a little yellow around the nipples and anus.<br>
<li><i>a<sup>e</sup>.</i> Extreme nonagouti. Recessive to the normal allele. Homozygotes are black, including around the nipples and anus.<br> </ul>