In the Cane Corso there are six basic coat colors that are accepted: Black, Black brindle, Fawn, Blue, Blue brindle, and Formentino.  There are varying shades of many of these and varying levels of bridling from more black/blue to more read showing.  This page is a thorough refresher on how canine coat color works and why certain colors present and not others.  It also sets the foundational basis for what genes carry some of the disqualifying alleles that we see within the breed.  Scientifically, tan points and brindle point are the same allele yet only one of these is a technical DQ in the standard.  It is important for breeders to understand simple Mendelian genetics if we hope to overcome some of the more common flaws within the breed.  Although many health issues can be viewed with simple Mendelian genetics, it is also prudent to point out that other traits are inherited on a much more complex level.