Callous-unemotional traits: Heritability likely lies at 36–67%; candidate gene studies implicate the serotonin & oxytocin systems in CU traits; no genome-wide loci for CU traits have yet been reported

The genetic underpinnings of callous-unemotional traits: A systematic research review. Ashlee A. Moore et al. Neuroscience & Biobehavioral Reviews, Volume 100, May 2019, Pages 85-97. https://doi.org/10.1016/j.neubiorev.2019.02.018

Highlights
•    Callous-unemotional (CU) traits represent the affective features of psychopathy.
•    The heritability of CU traits likely lies between 36–67%.
•    Candidate gene studies implicate the serotonin and oxytocin systems in CU traits.
•    Epigenetic changes to serotonin and oxytocin genes are associated with CU traits.
•    No genome-wide loci for CU traits have yet been reported.

Abstract
Background: Callous-unemotional (CU) traits represent the affective features of psychopathy used to delineate youth at high risk for externalizing pathology. The genetic etiology CU traits is not currently well-understood.

Methods: The current review surveyed the literature for studies on the genetic underpinnings of CU traits and integrated information from 39 genetic studies.

Results: The results from 24 studies with quantitative data suggest that the heritability for CU traits is likely between 36–67%. A majority of the 16 molecular genetic studies focused on candidate genes in the serotonin and oxytocin systems with results that have not been well replicated. Although two genome-wide association studies have been conducted, no genome-wide significant loci have been discovered.

Discussion: There is some evidence to suggest that the serotonin and oxytocin systems may play a role in CU traits; however, there is currently not enough evidence to implicate specific genetic mechanisms. The authors encourage researchers to continue to apply the most up-to-date and relevant methodology, specifically collaborations and consortiums using genome-wide and polygenic methods.