Objective: Disrupted-in-schizophrenia 1 (DISC1) has been linked to vulnerability to a variety of psychiatric disorders and neuropsychiatric phenotypes. However, DISC1 has not been frequently examined as a potential risk factor for substance dependence. An association between opioid dependence and DISC1 rs2738888 polymorphism has been recently reported. In addition, opioid dependence was associated with rs6419156 located close to the protein phosphatase 3 catalytic subunit alpha isoform (PPP3CA) gene. The aim of the present study was to examine the associations between opioid dependence with rs2738888 and rs6419156 in an independent sample.
Method: The selected polymorphisms were genotyped in a sample of 392 individuals (69.9% male) diagnosed as alcohol- and/or opioid-dependent. A control group (n = 257; 67.7% male) was derived from the Polish National Health Survey (N = 14,350).
Results: The frequency of rs2738888 C allele was higher in controls than in opioid-dependent cases (OR = 0.65, p = .045). Phenotypic-oriented analyses performed within opioid-dependent individuals revealed the association between lifetime suicide attempt and rs2738888. The C allele of rs2738888 had a protective effect on lifetime suicide attempt in opioid-dependent patients (OR = 0.25, p = .003). Rs6419156 was not associated with substance dependence in the examined sample.
Conclusions: The DISC1 may play an important role in vulnerability to opioid dependence. In addition, DISC1 may also be a genetic risk factor for suicide attempt in opioid-dependent individuals.