Locus Informationen: CR-Lokus
Inheritance: incomplete autosomal-dominant
→ Incomplete means that only one copy of the variant (Cr/n) is necessary to see a dilution in the color, giving the Palomino, Buckskin, and Smoky Black coat colors (although smoky black may look the same as normal black). With two copies of the Cream variant (Cr/Cr), the dilution effect is complete, giving the Cremello, Perlino, and Smoky Cream coat colors. These three variants can look nearly identical, so it is often necessary to test the base color genetic variants (Agouti, Extension) to determine which base color the horse has. The pictures in the graphic below show extreme examples, but most “double dilute” (Cr/Cr) horses do not appear so different in color.
- Cream reduces the amount of pigment produced in the skin cells and hair.
- With one copy of the Cream variant, less light/red pigment (phaomelanin) is produced. With two copies of the Cream variant, both light/red and dark (eumelanin) pigmnets are reduced.
- The Base color of the horse determines which dilute color they will be (see graphic below).
→ Two copies of the Cream variant (Smoky cream, perlino, cremello) can be very difficult to tell apart. It is often necessary to do a genetic test to determine the base colors (black, bay, chestnut).
Test informationen: This test detects a mutation in the SLC45A2 (MATP) gene.
Mariat, D., Taourit, S., Guerin, G.: A mutation in the MATP gene causes the cream coat colour in the horse Genetics Selection Evolution 35:119-33, 2003. Doi: 10.1051/gse:2002039.
More information can be found on the OMIA website: Online Mendelian Inheritance in Animals.