Polymorphisms in Arsenic(+III)methyltransferase (AS3MT) Predict Gene Expression of AS3MT as well as Arsenic Metabolism.

Karin Engström, Marie Vahter, Simona Jurkovic Mlakar, Gabriela Concha, Barbro Nermell, Rubhana Raqib, Alejandro Cardozo, Karin Broberg Palmgren

Research output: Contribution to journalArticlepeer-review


Background: Arsenic is mono- (MMA) and dimethylated (DMA) in humans and the methylation pattern demonstrates large inter-individual differences. The fraction of urinary MMA is a marker for susceptibility to arsenic-related diseases. Objectives: The impact of polymorphisms in five methyltransferase genes on arsenic metabolism was evaluated in two populations, one in South America, one in southeast Asia. The methyltransferase genes were arsenic(+III)methyltransferase (AS3MT), DNAmethyltransferase 1a and 3b (DNMT1a, DNMT3b), phosphatidylethanolamine Nmethyltransferase (PEMT) and betaine-homocysteine methyltransferase (BHMT). AS3MT expression was analyzed in peripheral blood. Methods: Subjects were women, exposed to arsenic in drinking water in the Argentinean Andes (N=172; median urinary arsenic 200 μg/L) and in rural Bangladesh (N=361; 100 μg/L, all in early pregnancy). Urinary arsenic metabolites were measured by HPLC-ICPMS. Polymorphisms (N=22) were genotyped with Sequenom™. AS3MT expression was measured with qPCR using TaqMan® expression assays. Results: Six AS3MT polymorphisms were significantly associated with arsenic metabolite patterns in both populations (p-values ≤0.01). The most frequent AS3MT haplotype in Bangladesh was associated with higher %MMA, and the most frequent in Argentina with lower %MMA and higher %DMA. Four polymorphisms in the DNMTs were associated with metabolite patterns in Bangladesh. Non-coding AS3MT polymorphisms affected gene expression of AS3MT in peripheral blood, demonstrating that one functional impact of AS3MT polymorphisms may be altering levels of gene expression. Conclusions: Polymorphisms in AS3MT significantly predicted As metabolism across these two very different populations, suggesting that AS3MT may have an impact on As metabolite patterns in populations worldwide.
Original languageEnglish
Pages (from-to)182-188
JournalEnvironmental Health Perspectives
Publication statusPublished - 2011

Subject classification (UKÄ)

  • Environmental Health and Occupational Health

Free keywords

  • AS3MT
  • arsenic
  • BHMT
  • DNMT1a
  • DNMT3b
  • gene expression
  • methylation
  • one-carbon metabolism
  • PEMT
  • polymorphism


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