Influence of polymorphic variants of the SLC6A4 gene on the frequency of detection of depressive states in the group of the clean/up workers of consequences of Chornobyl accident in the remote period after the Chornobyl catastrophe

Abstract

To determine the effect of polymorphic variants of the SLC6A4 gene on the frequency of detection of depression in a group of clean up workers in the remote period after the Chornobyl catastrophe. The study was conducted in a group of 59 victims of the Chornobyl NPP accident, divided into two groups (without depression and with depressive symptoms). The diagnosis of depressive disorders was based on a compre hensive assessment of the complaints of the surveyed, the clinical and psychopathological data, the values of the Zung Self Rating Depression Scale (SDS), the Brief Psychiatric Rating Scale (BPRS), the General Health Questionnaire (GHQ 28). DNA from the peripheral blood mononuclear cells was isolated, and the 5 HTTLPR polymorphism was determined by polymerase chain reaction (PCR). Depressive symptoms were more often found among reconvalescents of acute radiation sickness (ARS) than in the clean up workers without ARS: (p = 0.006). The tendencies of the association of the received dose of exter nal exposure with the number of points on the SDS scale (r = 0.284; p = 0.043), the sum of scores on the BPRS scale (r = 0.686; p = 0.001), depression (r = 0.323, p = 0.017) and its severity (r = 0.273; p = 0.051) were found. Among the examined clean up workers, in comparison with a large group of Europeans without mental disorders, an increase in the number of carriers of the genotype S/S SLC6A4 was found (p = 0.03). Only for the carriers of the S/S genotype, the reciprocal association between the development of depression and the age of the patient was found: r = 0.503 (p = 0.033), between the development of depression and the time from the ChNPP accident: r = 0.581 (p = 0.011), as well as positive correlation of development of depression with dose of irradiation: r = 0.515 (p = 0.025). Among people aged 55 and older, the development of depression was associated with a decrease in the frequency of high ly functional genotype LА/LА to 4.76% versus 31.25% in the absence of depressed symptoms (p = 0.042). In the group of younger patients, the distribution of genotypes did not differ depending on the signs of depression (p = 0.476). The pilot analysis of the distribution of genotypes of the SLC6A4 gene for polymorphisms of 5 HTTLPR and rs25531 in the clean up workers group showed the promise of further studies of the contribution of LА/LА і S/S genotypes to the development of depressive states in combination with the action of the radiation factor.