Published in BMC Genomics, this study aimed to identify genetic loci associated with breed-typical patterns of fear, anxiety, and aggression—traits that strongly affect canine welfare, human–dog relationships, and public safety. While the neurobiology of these emotions is well studied, their genetic foundations remain less understood.
The researchers conducted a genomewide association (GWA) study across several hundred dogs from diverse breeds, mapping behavioral stereotypes associated with fear and aggression. Findings were confirmed in a second cohort, and validated loci were used to predict behavioral tendencies in a third, previously unmapped group of breeds.
Two major findings emerged:
1) The well-known IGF1 and HMGA2 loci—best recognized for their influence on small body size—were associated with separation anxiety, touch-sensitivity, owner-directed aggression, and dog rivalry. These may represent cases where the same genetic variation influences both morphology and behavior.
2) Two additional loci showed strong and repeated associations with fear and aggression traits:
– A region between GNAT3 and CD36 on chromosome 18, and
– A region near IGSF1 on the X chromosome.
These loci influenced multiple behavioral traits, including non-social fear and fear or aggression toward unfamiliar humans and dogs. Notably, all four identified loci are among the most evolutionarily selected in the canine genome, hinting at their importance during domestication.
The authors propose that reduced-fear variants at GNAT3–CD36 and IGSF1 may have played a central role in enabling early dogs to coexist with humans. CD36, highly expressed in regions such as the amygdala and hypothalamus, aligns with known neurobiological pathways for fear and aggression. Mouse studies further support the gene’s relevance, as CD36 knockouts show increased anxiety and aggression.
Finally, within the X-linked region, the authors distinguish two closely linked behavioral loci despite extensive linkage disequilibrium: one associated with sociability (likely HS6ST2) and a separate one associated with fear/aggression.
This work advances understanding of the genomic architecture underlying canine emotional behavior and offers evolutionary insight into how domestication may have shaped temperament-related traits.
Source: Zapata, I., Serpell, J., & Alvarez, C. E. (2016). Genetic Mapping of Canine Fear and Aggression. BMC Genomics. Published August 8, 2016.
