The recessive mutation at agouti (a)

I just want to clarify a point.  Carrying the recessive mutation at agouti (a) does not mean that a horse does not have an agouti gene.  So often we use horse hand and say the horse doesn't have agouti but this is incorrect.  All horses have an Agouti gene.  The recessive mutation at agouti is caused by a deletion of a small portion of the agouti gene not the entire gene.  

I just realized I said "horse hand" instead of "short hand".  It was funny though so I didn't correct it.