(Curiosity vs. Vigilance)
Gene or region: DRD4
Reference allele: G
Mutant allele: A
Affected Breeds: Many
Research Confidence: Moderate confidence, findings replicated in multiple species
What it does:
Temperament is a complex trait influenced by multiple genetic and environmental factors. Individual components of temperament are potentially under different controls. Curiosity in the horse has been defined as an interest in novel objects and a willingness to approach them. Vigilance refers to the tendency of a horse to examine its surroundings carefully and from a safer distance. For this particular SNP, horses homozygous for the G allele (G/G) displayed both higher curiosity and lower vigilance scores, whereas horses with one or two A alleles (A/A and G/A) had lower curiosity and higher vigilance scores.
DRD4 encodes a member of the dopamine receptor family. Natural variations have been associated with novelty seeking behavior in a variety of human populations. Similarly, “knock-out” mutations in the mouse (where the gene was experimentally removed) result in a sharp decrease in exploratory behaviors. This mutation results in an amino acid change, which likely results in an alteration in function of the encoded protein.
Momozawa Y et al., “Association between equine temperament and polymorphisms in dopamine D4 receptor gene.” (2005) Mamm Genome. 16: 538-44. PMID: 16151699