Genetics & Biology What is the relationship between the extension gene and the agouti gene? February 9, 2026 by Riding What is the Relationship Between the Extension Gene and the Agouti Gene? The relationship between the extension gene and the agouti gene is crucial in determining the coat color of many animals, particularly in mammals like horses, dogs, and mice. The extension gene controls the production of eumelanin (black or brown pigments), while the agouti […] Read more »