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Monday, December 6, 2010

Maternal antioxidant SNPs modify link between acetaminophen exposure in utero and childhood asthma

Shaheen and colleagues report their findings from studies on acetaminophen and childhood asthma from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort in this month’s issue (Shaheen SO, Newson RB, Rose-Zerilli MJ, Holloway JW, Henderson AJ. Prenatal and infant acetaminophen exposure, antioxidant gene polymorphisms, and childhood asthma. J Allergy Clin Immunol 2010;126:1141-1148.e7). The authors follow up on their previous studies demonstrating association of childhood asthma with acetaminophen use in pregnancy by investigating possible causality between the two.

Shaheen et al. reason that prenatal acetaminophen exposure may increase the risk of childhood asthma by increasing oxidative stress and glutathione depletion and that polymorphisms in antioxidant genes may influence acetaminophen toxicity in the womb. They genotyped transcription factor nuclear erythroid 2 p45-related factor 2 (Nrf2), a primary regulator of antioxidant genes, and the glutathione-S-transferases GSTM1, -P1, and T1, which protect the lung from oxidative stress. Previous research has shown that Nrf2-negative mice readily develop liver toxicity in response to acetaminophen exposure.

The authors find that early [≤20 weeks gestation] and late [≥20 weeks gestation] acetaminophen exposure in utero is associated with increased risk for wheezing and asthma in childhood. Late gestation acetaminophen exposure has a more profound effect on wheezing and, in addition, is associated with increased serum IgE.

They also find that effects of prenatal acetaminophen exposure on asthma risk are modified by Nrf2 and GST variants in the mother, but not in the child, strengthening evidence that the link between acetaminophen use in pregnancy and childhood asthma may be causal.

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