One copy of this mutation will dilute red pigment while two copies dilutes both red and black pigment
Breeds known to carry this mutation
Cream dilution is responsible for palomino, buckskin, smoky black, cremello, perlino and smoky cream coat colours. Cream dilution is caused by a mutation in the MATP gene.
If one copy of cream is detected (Cr/n), then only red pigment is diluted and the horse is palomino, buckskin or smoky black, depending on its base colour (chestnut, bay and black respectively). If two copies are detected (Cr/Cr), the horse is diluted to cremello (chestnut base), perlino (bay base) or smoky cream (black base). Double dilute horses also have blue eyes and pink skin. It is usually not possible to accurately determine a double dilutes base colour without genetic testing.
Interpretation of results
n/n: Horse does not the carry cream dilution allele.
Cr/n: Horse is heterozygous for the cream dilution allele. The horse will have diluted red pigment and be palomino (base colour chestnut), buckskin (base colour bay) or smoky black (base colour black, not easily discernable from a normal black coat).
Cr/Cr: Horse has two copies of the cream dilution allele and is a double dilute (cremello, perlino or smoky cream).
Reference Mariat et al. A mutation in the MATP gene causes the cream coat colour in the horse.
Genetics Selection Evolution 2003; 35(1), 119-133. doi: 10.1051/gse:2002039