title: Arsenic exposure in early pregnancy alters genome-wide DNA methylation in cord blood, particularly in boys.
abstract: Early-life inorganic arsenic exposure influences not only child health and development but also health in later life. The adverse effects of arsenic may be mediated by epigenetic mechanisms, as there are indications that arsenic causes altered DNA methylation of cancer-related genes. The objective was to assess effects of arsenic on genome-wide DNA methylation in newborns. We studied 127 mothers and cord blood of their infants. Arsenic exposure in early and late pregnancy was assessed by concentrations of arsenic metabolites in maternal urine, measured by high performance liquid chromatography-inductively coupled plasma mass spectrometry. Genome-wide 5-methylcytosine methylation in mononuclear cells from cord blood was analyzed by Infinium HumanMethylation450K BeadChip. Urinary arsenic in early gestation was associated with cord blood DNA methylation (Kolmogorov-Smirnov test, P-value<10-15), with more pronounced effects in boys than in girls. In boys, 372 (74%) of the 500 top CpG sites showed lower methylation with increasing arsenic exposure (r S -values>-0.62), but in girls only 207 (41%) showed inverse correlation (r S -values>-0.54). Three CpG sites in boys (cg15255455, cg13659051 and cg17646418), but none in girls, were significantly correlated with arsenic after adjustment for multiple comparisons. The associations between arsenic and DNA methylation were robust in multivariable-adjusted linear regression models. Much weaker associations were observed with arsenic exposure in late compared with early gestation. Pathway analysis showed overrepresentation of affected cancer-related genes in boys, but not in girls. In conclusion, early prenatal arsenic exposure appears to decrease DNA methylation in boys. Associations between early exposure and DNA methylation might reflect interference with de novo DNA methylation.
authors: 1Institute of Environmental Medicine,Unit of Metals and Health,Karolinska Institutet,Stockholm,Sweden.
authors: K
authors: K
authors: Broberg
authors: 1Institute of Environmental Medicine,Unit of Metals and Health,Karolinska Institutet,Stockholm,Sweden.
authors: S
authors: S
authors: Ahmed
authors: 2Department of Laboratory Medicine,Section of Occupational and Environmental Medicine,Lund University,Lund,Sweden.
authors: K
authors: K
authors: Engström
authors: 1Institute of Environmental Medicine,Unit of Metals and Health,Karolinska Institutet,Stockholm,Sweden.
authors: M B
authors: MB
authors: Hossain
authors: 4Department of Clinical Biochemistry, Faculty of Pharmacy,University of Ljubljana,Ljubljana,Slovenia.
authors: S
authors: S
authors: Jurkovic Mlakar
authors: 5Unit of Biostatistics,Institute of Environmental Medicine,Karolinska Institutet,Stockholm,Sweden.
authors: M
authors: M
authors: Bottai
authors: 1Institute of Environmental Medicine,Unit of Metals and Health,Karolinska Institutet,Stockholm,Sweden.
authors: M
authors: M
authors: Grandér
authors: 3International Centre for Diarrhoeal Disease Research Bangladesh (ICDDR,B),Dhaka,Bangladesh.
authors: R
authors: R
authors: Raqib
authors: 1Institute of Environmental Medicine,Unit of Metals and Health,Karolinska Institutet,Stockholm,Sweden.
authors: M
authors: M
authors: Vahter
mesh_terms: D001151:Arsenic / Q000009:adverse effects* / Q000097:blood / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects*; D005260:Female; D005312:Fetal Blood / Q000737:chemistry*; D006801:Humans; D007231:Infant, Newborn; D016014:Linear Models; D008297:Male; D013058:Mass Spectrometry; D018811:Maternal Exposure / Q000009:adverse effects*; D008431:Maternal-Fetal Exchange / Q000502:physiology*; D011247:Pregnancy; D025341:Principal Component Analysis; D012727:Sex Characteristics; D018709:Statistics, Nonparametric
chemical_list: D001151:Arsenic