title: Congenital heart defects and biomarkers of methylation in children: a case-control study.
abstract: BACKGROUND
  Derangements in the maternal methylation pathway, expressed by global hypomethylation and hyperhomocysteinemia, are associated with the risk of having a child with a congenital heart defect (CHD). It is not known whether periconception exposure to these metabolic derangements contributes to chromosome segregation and metabolic programming of this pathway in the foetus.
  
  
  METHODS
  In a Dutch population-based case-control study of 143 children with CHD and 186 healthy children, we investigated S-adenosylmethionine (SAM), S-adenosylhomocysteine (SAH), total homocysteine (tHcy), the vitamins folate and B12 and the functional single nucleotide polymorphisms in the folate gene MTHFR 677C>T and 1298A>C. Comparisons were made between cases and controls adjusting for age, medication, vitamin use and CHD family history.
  
  
  RESULTS
  In the overall CHD group, the median concentrations of SAM (P = 0·011), folate in serum (P = 0·021) and RBC (P = 0·030) were significantly higher than in the controls. Subgroup analysis showed that this was mainly attributable to complex CHD with higher SAM (P < 0·001), SAH (P = 0·012) and serum folate (P = 0·010) independent of carriership of MTHFR polymorphisms. Highest concentrations of SAM, SAH and folate RBC were observed in complex syndromic CHD. The subgroup of children with Down syndrome, however, showed significantly higher SAH (P = 0·037) and significantly lower SAM:SAH ratio (P = 0·034) compared with other complex CHD, suggesting a state of global hypomethylation.
  
  
  CONCLUSIONS
  High concentrations of methylation biomarkers in very young children are associated with complex CHD. Down syndrome and CHD may be associated with a global hypomethylation status, which has to be confirmed in tissues and global DNA methylation in future studies.
authors.affiliation: Department of Obstetrics and Gynaecology/Division of Obstetrics and Prenatal Medicine, Erasmus MC, University Medical Centre, Rotterdam, the Netherlands.
authors.forename: Sylvia A
authors.initials: SA
authors.lastname: Obermann-Borst
authors.forename: Lydi M J W
authors.initials: LM
authors.lastname: van Driel
authors.forename: Willem A
authors.initials: WA
authors.lastname: Helbing
authors.forename: Robert
authors.initials: R
authors.lastname: de Jonge
authors.forename: Mark F
authors.initials: MF
authors.lastname: Wildhagen
authors.forename: Eric A P
authors.initials: EA
authors.lastname: Steegers
authors.forename: Régine P M
authors.initials: RP
authors.lastname: Steegers-Theunissen
mesh_terms: D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D016022:Case-Control Studies; D002675:Child, Preschool; D004314:Down Syndrome / Q000235:genetics*; D005260:Female; D005492:Folic Acid / Q000097:blood / Q000378:metabolism*; D006330:Heart Defects, Congenital / Q000235:genetics*; D006801:Humans; D020138:Hyperhomocysteinemia / Q000150:complications*; D007223:Infant; D008297:Male; D008745:Methylation; D009426:Netherlands; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000235:genetics / Q000378:metabolism*; D012307:Risk Factors; D014805:Vitamin B 12 / Q000097:blood / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D005492:Folic Acid; D014805:Vitamin B 12