Parasuicidal Patients in the Emergency Department and Their Relationship with Cannabinoid Gene Polymorphism

Background: Suicidal behavior represents a serious public health problem. Studies about twins, adoption, and family conflicts have shown a relationship between genetics and suicide. CB1 receptors are coded by the cannabinoid-1 receptor (CNR1) gene. It was shown that the CNR1 gene polymorphism (1359 G/A) is associated with many neuropsychiatric disorders, including major depression. Objective: Our aim is to study whether there is an association between the polymorphism of the CNB1 receptor and suicide attempts. We compared non-suicide subjects with suicide-attempt victims to substantiate these findings. Materials and Methods: Peripheral blood samples were drawn from all of the participants, and single nucleotide polymorphism (SNP) of the cannabinoid gene (1359 G/A) was analyzed. Results: The study included 115 suicide attempts (parasuicide patients) (mean age 25.6±8.5; 41 males, 74 females) and 69 unrelated healthy subjects (mean age 27.5±10.6; 38 males, 31 females). The genotype distributions were significantly different between the parasuicide and control groups and this difference was attributed to the AG genotype rates (21.7% vs 44.9%, p=0.001). Having AG genotype lowered the admittance to ED due to parasuicide 3.3 times (95% CI: 1.6-6.8). The frequencies of A and G alleles in the CNR1 gene polymorphism were 16.1%). (n=37) and 83.9% (n=193) in parasuicide patients and 22.5% (n=31) and 77.5% (n=107) in the control group, respectively (p=0.127). All the subjects with the AA genotype were in the parasuicide group (n=6). The frequency of the AG genotype was significantly lower in parasuicide patients with a previous psychiatric diagnosis compared to suicide attempts without a previous diagnosis (32% (n=8) vs. 68% (n=17); p=0.004). Conclusion: There is a preventive association between the CNR1 rs1049353 (1359 G/A) gene polymorphism and parasuicide patients. The CNR1 receptor polymorphism may be used as a biological test to help predict and prevent suicide intentions if the relationship can be proved with further studies.