Dioxin-metabolizing genes in relation to effects of prenatal dioxin levels and reduced birth size: The Hokkaido study

•We examined the association of prenatal dioxins and polymorphism with birth size.•Polymorphisms in 3 genes encoding dioxin-metabolizing enzymes were investigated.•Polymorphisms were analyzed in 421 healthy pregnant Japanese women.•Dioxin TEQ was associated with reduced birth weight reduction in the GSTM1 null genotype.

ObjectivesWe investigated the effects of maternal polymorphisms in 3 genes encoding dioxin-metabolizing enzymes in relation to prenatal dioxin levels on infant birth size in Japan.MethodsWe examined the relationship between dioxin exposure and birth size in relation to the polymorphisms in the genes encoding aromatic hydrocarbon receptor (AHR [G > A, Arg554Lys]), cytochrome P450 (CYP) 1A1 (T6235C), and glutathione S-transferase mu 1 (GSTM1; Non-null/null) in 421 participants using multiple linear regression models.ResultsIn mothers carrying the GSTM1 null genotype, a ten-fold increase in total dioxin toxic equivalency was correlated with a decrease in birth weight of −345 g (95% confidence interval: −584, −105).ConclusionsWe observed adverse effects of maternal GSTM1 null genotype on birth weight in the presence of dioxins exposure during pregnancy.