A-gene

 

This gene controles whether you can se the tabby pattern or not.
It gives the difference between the non-agouti (self or solid) and the agouti (the tabby-pattern Tick Tabby, Spotted Tabby, Mackerel Tabby and Blotched/Classic Tabby.

The agouti dominates the non-agouti.

[AA] and [Aa] is the agouti (you can se the tabby pattern)
[aa] is the non-agouti (you canot se the tabby patern)