Polymorphisms of the OPRM1, OPRK1, and DCC Genes and Non-Suicidal Self-Harming in Adults

Objective. To assess the impact of polymorphisms rs1779971 of the OPRM1 gene, rs6473797 of the OPRK1 gene, and rs8084280 of the DCC gene on the characteristics and motivators of non-suicidal self-harm (NSSH) in adults. Materials and methods. The pilot sample studied here consisted of 28 patients with NSSH (25 women (89.3%), median [Q₁–Q₃] age 23 [21.25–25] years). The majority of patients (n = 20, 78.6%) had bipolar disorder. The characteristics and motivators of NSSH were assessed using the Inventory of Statements about Self-Injury (ISAS) scale. The Childhood Trauma Questionnaire (CTQ) was used to measure childhood trauma, which is the most important environmental factor associated with NSSH. The Baratt Impulsivity Scale (BIS) and Buss–Perry Aggression Questionnaire (BPAQ) were also used, to assess impulsivity and aggressiveness respectively. Genotyping was performed using real-time PCR and genetic effects were assessed using a dominance model. Statistical analysis used the Mann–Whitney U test, Pearson’s χ² test, and multiple linear regression. Results. Carriers of the minor G allele at rs1799971 of the OPRM1 gene had a higher level of aggression on the BPAQ scale (p = 0.02). The presence of the minor C allele of the rs6473797 polymorphism of the OPRK1 gene was associated with an increase in the severity of the NSSH motivators Affect regulation (B = 2.23; 95% CI (0.39–4.06); p = 0.022) and Antidissociation (B = 3.31; 95% CI (0.18–6.44); p = 0.039), while the minor T allele of rs8084280 of the DCC gene, conversely, reduced the level of the motivator Affect regulation (B = –1.74; 95% CI (–3.30 –0.18); p = 0.032). These effects were found after adjustment for diagnosis, gender, age, and the presence of childhood trauma. Conclusions. To our knowledge, this is the first study of the association of genetic markers with motivators of NSSH. The results of this pilot study demonstrate that polymorphisms in the OPRK1 and DCC genes may determine differences in motivation to self-harm, but the results require confirmation in larger samples.