Friesian

Dwarfism in Friesians is an inherited disorder characterized by a disproportionate growth with reduced bone length of limbs and ribs while the size of the head and length of the back are normal.

Tobiano is a white spotting pattern characterized by white on the body that crosses the topline.

The extension gene, or red factor, determines whether a horse will have a chestnut base coat color or a black or bay base coat color.

Dominant white is a variable white spotting pattern caused by many different mutations in the KIT gene. The VGL tests for the five most common mutations known as W5, W10, W13, W20, and W22. Homozygosity for W5, W10, W13 or W22 is thought to be non-viable.

Cream is a dilution that causes the palomino, buckskin, smoky black, cremello, perlino, and smoky cream coat colors.

The agouti gene controls the distribution of black pigment, and determines whether a horse will have a bay or black base coat color.