Combinations of unfavorable genotypes of polymorphic variants of the GSTM1, GSTP1, and HSPA1B genes in a population sample of residents of Eastern Siberia and in professionally exposed cohorts

Earlier, the environmental problems of the effects of mercury pollution on the environment at the industrial site of the mercury electrolysis workshop of Usolyokhimprom LLC in the Irkutsk region were discussed. Surveys were conducted among former employees and the contingent involved in liquidation measures, which made it possible to outline approaches to identifying individuals with a potential risk of negative health effects.

The study aims to consider combinations of unfavorable genotypes of polymorphic variants of the GSTM1, GSTP1, and HSPA1B genes in a population sample of residents of Eastern Siberia and compare them with those in cohorts exposed to occupational exposure to identify the risk of mercury intoxication.

The authors studied polymorphic variants of the GSTP1 (Ile105Val, rs1695), GSTP1 (Ala114Val, rs1138272) and GSTM1 genes by PCR-RV in 92 residents of the Usolsky district. In addition, the HSPA1B polymorphism (1267A/G, rs1061581) was additionally investigated by embedded PCR in 144 employees of the Federal Environmental Operator (FEO) who participated in the elimination of accumulated damage at the industrial site of the enterprise.

Analysis of HSPA1B genotypes combinations with two or three adverse GST genotypes revealed 6 (0.07) individuals with the GG-HSPA1B genotype in examined sample. That was comparable with the frequency of those in the Ministry of Emergency Situations (MES) group (0.05) and more than twice exceeded the combination frequency in FEO employees group of (0.03). Among former workers, carriage of similar genotype combinations was established in 6 (0.07) patients with chronic mercury intoxication (CMI) whereas no combinations were detected in group of long-term workers without CMI. Two patients with CMI and three firefighters from the MES (0.02 in both cases) were identified as carriers of three adverse GST genotypes in combination with a GG homozygote with the absence of such combinations in other groups.

The authors conducted a study of polymorphic loci of GSTM1, GSTP1, and HSPA1B genes in a population sample of Eastern Siberia residents followed by the analysis of adverse genotype combinations compared with those in occupationally exposed to mercury cohorts. Individuals with a combination of two or three adverse GST genotypes with the GG-HSPA1B genotype which is associated with a high prognostic risk of CMI development were identified in the examined sample. The latter is essential since the surveyed sample can potentially be considered as a cross-section of the future workforce engaged in the recultivation of Usolyekhimprom LLC mercury contaminated zone and the construction or operation of the objects of the planned environmental technology park.

Limitations. Limitations include both the relatively small size of the examined sample and the lack of data on the deletion polymorphism of the GSTT1 gene for this group, previously obtained for professionally exposed cohorts.

Ethics. Voluntary informed consent was obtained from each subject, approved by the local committee on Biomedical ethics (Protocol No. 6 dated 03/10/2020).

Contributions:
Chernyak Yu.I. — concept, research design, data analysis and interpretation, writing and editing text;
Larionova K.V. — performing techniques, data analysis, writing text;
Lakhman O.L. — making fundamental changes and editing the text.

Gratitude. The authors express their gratitude to the staff of the Institute's clinic for organizing the examination and forming groups.

Funding. The work was carried out within the Framework of the state assignment of the East-Siberian Institute of Medical and Ecological Research (No. 123032000010-8).

Conflict of interest. The authors declare no conflict of interest.

Received: 29.09.2025 / Accepted: 06.10.2025 / Published: 30.10.2025

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