Single-Nucleotide Variant rs167771 of the DRD3 Gene Does Not Increase the Risk of Developing Antipsychotic-Induced Parkinsonism in Schizophrenic Patients

Antipsychotic-induced parkinsonism (AIP) is a form of secondary parkinsonism that most often develops with blockade of dopaminergic receptors type D2. However, AIP can oc-cur not only while taking first-generation APs, but also new ones that have a wider receptor pro-file. There is a connection between the DRD3 gene and the regulation of motor activity in associa-tion genetic studies of AIP; Aim : to study the role of single-nucleotide variant rs167771 of the DRD3 gene, encoding dopaminergic receptors D3 type, with the risk of AIP in Caucasian patients with schizophrenia spectrum disorders (SSDs) of North-West Russia; Methods : The study in-volved 91 participants permanently residing in Saint Petersburg and the Leningrad region (North-West Russia), including: group 1 - 30 patients (SSDs with AIP); group 2 - 29 patients (SSDs without AIP); group 3 (control) - 32 healthy volunteers. All participants underwent: a neurological exami-nation using scales and questionnaires (H&Y, MoCa, UPDRS, BARS, AIMS, ESRS) at two points (before and after 8 weeks on AP monotherapy) and an association genetic study of carriage of major and minor alleles and genotypes of rs167771 of the DRD3 gene with a risk of developing AIP; Results : According to the study, it was shown that AIP is characterized by bradykinesia with a decrease in the amplitude of multidirectional movements. Mild/moderate asymmetry in the severity of action tremor according to the hemi-type on the left. The allelic frequency of the stud-ied rs167771 of the DRD3 gene in Caucasians of North-West Russia was comparable to that in the countries of Northern Europe, also in the countries of Southeast Asia and some regions of North and South America. The obtained clinical data are typical for the early stage of development of AIP, which is missed in more than 80% of cases by the 8th week from the start of taking AP. The major allele A of rs167771 of the DRD3 gene is protective against the risk of SSDs (OR < 0.001), but not AIP (OR > 0.05); Conclusions : We have not found a significant association of rs167771 of the DRD3 gene with the risk of developing AIP in Caucasians in North-West Russia.