Callous and unemotional traits (CU) are distinguished by a persistent pattern of behavior that reflects a disregard for others, and also a lack of empathy and generally deficient affect. The interplay between genetic and environmental risk factors may play a role in the expression of these traits as a conduct disorder (CD). A CU specifier has been included as a feature of conduct disorder in the fifth revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5).