title: Cognitive function in adolescence: testing for interactions between breast-feeding and FADS2 polymorphisms.
abstract: OBJECTIVE
  Breast-fed C-allele carriers of the rs174575 single nucleotide polymorphism in the fatty acyl desaturase 2 (FADS2) gene have been reported to show a 6.4 to 7 IQ point advantage over formula-fed C-allele carriers, with no effect of breast-feeding in GG carriers. An Australian sample was examined to determine if an interaction between breast-feeding and the rs174575 single nucleotide polymorphism had any effect on IQ.
  
  
  METHODS
  This hypothesis was tested in more than 700 families of adolescent twins assessed for IQ and breast-feeding, birth weight, and FADS2 polymorphisms, and parental socioeconomic status and education, and maternal FADS2 status.
  
  
  RESULTS
  No significant evidence for a moderating effect on IQ of rs174575 C-carrier status and breast-feeding was found, and there no effects of maternal FADS2 status on offspring IQ. In addition, no main effects of any FADS2 polymorphisms on IQ were found when the genotype was kept as two-homozygote and one-heterozygote categories and indeed no evidence for effects of breast-feeding on IQ scores after controlling for parental socioeconomic status and education. The investigation was extended to two additional FADS2 polymorphisms (rs1535 and rs174583), but again, although these polymorphisms code alleles affecting fatty acid metabolism, no main or interaction effects were found on IQ.
  
  
  CONCLUSIONS
  These results support the view that apparent effects of breast-feeding on IQ reflect differential likelihood of breast-feeding as a function of parental education and did not support the predicted interaction effect of FADS2 and breast-feeding on IQ.
authors.affiliation: Queensland Institute of Medical Research, Royal Brisbane Hospital, Brisbane, QLD 4029, Australia. nico.martin@qimr.edu.au
authors.forename: Nicolas W
authors.initials: NW
authors.lastname: Martin
authors.forename: Beben
authors.initials: B
authors.lastname: Benyamin
authors.forename: Narelle K
authors.initials: NK
authors.lastname: Hansell
authors.forename: Grant W
authors.initials: GW
authors.lastname: Montgomery
authors.forename: Nicholas G
authors.initials: NG
authors.lastname: Martin
authors.forename: Margaret J
authors.initials: MJ
authors.lastname: Wright
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Bates
mesh_terms: D000293:Adolescent; D001315:Australia; D001942:Breast Feeding / Q000523:psychology*; D003071:Cognition / Q000502:physiology*; D004777:Environment; D005190:Family / Q000523:psychology; D044943:Fatty Acid Desaturases / Q000502:physiology*; D005260:Female; D006580:Genetic Carrier Screening; D006801:Humans; D007361:Intelligence Tests; D008297:Male; D016743:Mental Competency / Q000523:psychology; D020641:Polymorphism, Single Nucleotide; D012959:Socioeconomic Factors; D055815:Young Adult
chemical_list: D044943:Fatty Acid Desaturases; C533241:FADS2 protein, human