One Copy of the Gene is Present = Heterozygous = One gene is capitalized, the other is lowercase i.e. Ee or Crcr. It can also be represented as n/Cr or n/Prl for the dilute and modifier genes.
Horse coat color genes come in pairs. For each color gene listed in this article, a horses genetic makeup is one of these three options:
Two Copies of the Gene are Present = Homozygous = Both genes capitalized i.e. EE or CrCr (first letter capitalized for notations with more than one letter).