It is understood that an individual's genotype, regardless of species, codes to produce proteins that form each individual. Genotype also codes for the production of neurotransmitters and hormones within the body. A region of DNA on chromosome 12 has been identified as the coding region for the Dopamine Receptor D4 gene in horses, otherwise known as "DRD4"; this gene has been widely studied within humans, dogs, and horses, showing correlations with certain behavioral traits. One such study explained that understanding a horse's "predisposed" behavior based on the individual's DNA, and the DRD4 gene, would allow handlers and trainers to "develop methods of management or training better suited to each breed." The purpose of this study was to further the research of DRD4 and the potential correlation it has to behavior, using a study group with minimal variables.
