title: Infant C677T MTHFR polymorphism and severe mental retardation.
abstract: BACKGROUND
  We investigated whether infants with homozygous genotype TT of the MTHFR gene were at increased risk of severe mental retardation.
  
  
  METHODS
  One hundred children with severe mental retardation (cases) were investigated from a large geographic-based study of infants born in California in 1992-1993. Cases were compared to 743 randomly selected nonmalformed control infants born in California during 1987-1991. DNA was extracted from newborn screening filter papers. Cases and controls were genotyped TT if homozygous for the MTHFR C677T allele, CT if heterozygous for the C677T allele, and CC if homozygous for the C677 (wild type) allele.
  
  
  RESULTS
  Overall, case and control infants had similar percentages of TT and CT genotypes. Percentages between cases and controls differed somewhat across race/ethnic groups. Elevated ORs of 1.9 (95% CI: 0.7-5.0) and 2.6 (95% CI: 1.1-5.8) were observed for the TT and CT genotypes, respectively, among Hispanic children. Observed results were not substantially altered for analyses that removed 41 case children who also had structural birth defects.
  
  
  CONCLUSIONS
  Folate-related mechanisms are important to investigate for etiologies of birth defects, and such lines of inquiry may be revealing for mental retardation given the relationships between mental retardation and birth defects and potential relationships between folate, DNA methylation, and mental retardation.
authors.affiliation: California Birth Defects Monitoring Program, Berkeley, California 94710, USA. gsh@cbdmp.org
authors.forename: Gary M
authors.initials: GM
authors.lastname: Shaw
authors.forename: Laura
authors.initials: L
authors.lastname: Jelliffe-Pawlowski
authors.forename: Verne
authors.initials: V
authors.lastname: Nelson
authors.forename: Huiping
authors.initials: H
authors.lastname: Zhu
authors.forename: John A
authors.initials: JA
authors.lastname: Harris
authors.forename: Richard H
authors.initials: RH
authors.lastname: Finnell
mesh_terms: D000483:Alleles; D000013:Congenital Abnormalities / Q000209:etiology; D005260:Female; D005492:Folic Acid / Q000008:administration & dosage; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006720:Homozygote; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008607:Intellectual Disability / Q000453:epidemiology / Q000208:ethnology / Q000235:genetics*; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors
chemical_list: D005492:Folic Acid; D042965:Methylenetetrahydrofolate Reductase (NADPH2)