From Leopard Gecko Wiki
Incomplete Dominate Gene
A gene which is Incomplete Dominate has generally has three different appearances. The gecko homozygous for the trait and homozygous not for the trait will look different. In Leopard Geckos, the Mack Snow trait is thought to be Incomplete Dominate. In our example, a Super Snow would be homozygous for the trait, while a normal would be a homozygous non trait carrier. This is where the heterozygous form comes in. With Incomplete Dominance, the heterozygous form of the trait is a blend of the two. For example, a Mack Snow starts out as a black and white hatchling, then tends to develop some yellowing. The yellowing comes from the normal. It is a blend between a normal and a Super Snow.
Incomplete Dominance in Leopard Geckos
Currently, the only Incomplete Dominate trait in Leopard Geckos is the Mack Snow. test