Cytochrome P450 family genes (CYPs) have common polymorphisms, which are evaluated for pesticide-induced oxidative stress susceptibility. Variant alleles in CYP enzymes may uncover susceptibility biomarkers of environmental toxicity. This study aims to investigate the relationship between CYP2D6 (G1934A) gene polymorphisms and chronic pesticide exposures, and to evaluate the association between CYP2D6 (G1934A) gene polymorphism on biochemical and hematological parameters. A cross-sectional study was carried out at a health promoting hospital, Suphan Buri, Thailand. Rice farmers and a control group (n = 50 for each) were recruited and their personal data were collected. Their blood samples were obtained by venepuncture and drawn into plain and Ethylenediaminetetraacetic acid (EDTA) tubes. Serum cholinesterase (SChE), liver function test, kidney function test, and complete blood count were assessed using automatic analyzers; and CYP2D6 (G1934A) genotyping was carried out by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). SChE in rice farmers was significantly lower (p = 0.033), which may be related to the use of chlorpyrifos. The genotypes were significantly different between rice farmers and the control group (p = 0.0001), and the GA variant in rice farmers was more frequent. The CYP2D6 (G1934A) (rs 3892097)) gene and SChE level were negatively correlated (r = −0.258, p = 0.009). However, other biochemical parameters were not different. Blood indices, including mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV), and mean corpuscular hemoglobin concentration (MCHC), values of rice farmers were significantly lower than the control group; and MCH, MCV, and MCHC values of the GA variant were also significantly lower than the wild type. The GA genotype was associated with hematological toxicity of organophosphate metabolite in chronic exposures.
Key words: blood indices, cholinesterase inhibitors, chronic pesticide exposure, CYP2D6, cytochrome P450, organophosphate
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