The Agouti Locus, more commonly known as the A Locus, has three distinctly different genes, ‘A,’ ‘a(t),’ and ‘a,’ that control the placement of color on the hair shaft. The A Locus does not determine color, but instead dictates pattern.
Agouti ‘A’ Gene
- Most dominant gene in the A Locus
- Creates bands of color on the hair shaft and causes white circles around the eyes, bellies, ears, and under the tail.
- The agouti gene is completely dominant so it is notated as A_
- Common colors caused by the Agouti gene are the chestnut agoutis, chinchilla variations, and steel.
Tan ‘a(t)’ Gene
- The tan gene is dominant over the ‘a’ gene but is recessive to the dominant ‘A’.
- This gene creates gold or silver ticking over the original color.
- Common colors include Silver Marten and Black Otter.
Self ‘a’ Gene
- The most recessive gene on the Agouti Locus, so when it is expressed, it is always going to be homozygous and will be notated as ‘aa.’
- This gene removes bands of color on the hair shaft.
- Common colors are Chocolate, Black, and Blue.
To view a picture dictionary of the many colors affected by the Agouti Gene check out the Color Guide!