Cream Dilution

Description

The Cream dilution gene lightens a horse’s coat by diluting both red and black pigment, with a much stronger effect on red. In many breeds this is considered a highly desirable trait. Cream is responsible for the palomino, buckskin, cremello, perlino, smoky black, and smoky cream colors.

Cream shows incomplete dominance, so the number of copies a horse carries determines how strong the dilution is.

Horses with one copy (n/Cr) are single dilutes, or heterozygous for Cream, and have a 50% chance of passing the gene to each foal. A bay horse with one copy is a buckskin, a chestnut or sorrel horse is a palomino, and a black horse is a smoky black. Because Cream has little effect on black pigment in a single dose, smoky blacks often look like ordinary black horses and may only be identified by testing.

Horses with two copies (Cr/Cr) are double dilutes, or homozygous for Cream, and always pass a copy to their foals. Double dilutes have a pale cream coat, blue eyes, and pink skin. A bay horse with two copies is a perlino, a chestnut or sorrel horse is a cremello, and a black horse is a smoky cream.

Cream dilution is caused by a mutation in the SLC45A2 gene, also known as MATP, which plays a role in the production of melanin. Other genes can produce similar lightening effects, and those are not detected by this test.

Effect on base color

• No dilution (n/n): chestnut or sorrel, bay, black
• Single dilute (n/Cr): palomino, buckskin, smoky black
• Double dilute (Cr/Cr): cremello, perlino, smoky cream

Why test for Cream?

Animal Genetics tests for the mutation responsible for Cream dilution and reports whether a horse is n/n, n/Cr, or Cr/Cr. Testing is useful when genetic confirmation is required, when a smoky black needs to be distinguished from a true black, or when a lightened coat could be caused by another gene such as Champagne, Pearl, or Gray.

This test confirms whether a horse carries Cream, but because the color name depends on the base coat, determining the exact color (buckskin, palomino, and so on) means running this test alongside the Red Factor and Agouti tests.

Possible results

Genotype	Description
Cr/Cr	Homozygous: Horse has two copies of the Cream Dilution gene and will appear as a double dilute of its base coat. Horse will pass one copy to all offspring.
n/Cr	Heterozygous: Horse has one copy of the Cream Dilution gene and will appear as a single dilute of its base coat. Each foal has a 50% chance of inheriting it.
n/n	Negative: Horse does not carry the Cream Dilution gene.

Breeds Affected

All breeds

Reference

A mutation in the MATP gene causes the cream coat colour in the horse.

The cream dilution gene, responsible for the palomino and buckskin coat colours, maps to horse chromosome 21.

Related Tests

• Pearl Dilution — a variant of the same gene; one copy of each produces a double-dilute look
• Champagne Dilution — a separate dilution often mistaken for cream
• Red/Black Factor — needed to name the exact color a cream dilute will be

Testing more than one color trait? The Color Panel includes this test plus seven others for $75.