Objectives:
The aim of the study was to determine relationships between the selected DRD2 gene polymorphisms and drug addiction.

Methods:
One hundred drug abusers undergoing treatment were recruited from the inpatient psychiatric centers in Poland. All participants were screened by means of the clinical interview SSAGA to describe the clinical picture. In the second part of the study, participants were examined using psychometric tools assessing selected psychopathological features. After that, blood samples were collected for a DNA isolation. The following DRD2 single nucleotide polymorphisms (SNPs) of the dopamine gene were genotyped: rs1800498 polymorphism of DRD2 gene (NC_000011.10:g.113420866G>A, GRCh38.p7); rs1079597 polymorphism of DRD2 gene (NC_000011.10:g.113425564C>T, GRCh38.p7); rs1076560 polymorphism of DRD2 gene (NC_000011.10:g.113412966C>A, GRCh38.p7).

Results:
The rs1800498 polymorphism has shown an association with drug abuse in which a higher frequency of the allelic T form was observed in the whole group of patients and selected subgroups with concomitant opiates or cannabis abuse history when compared with the controls.

Conclusions:
In the presented study, one of selected polymorphisms of DRD2 gene, revealed to be correlated with substance use disorder (at the limit of statistical significance), which could suggest its impact on dependence endophenotype. The presented research was a pilot study, so it requires replication on a larger group of patients to verify and confirm obtained outcomes.