title: Apolipoprotein E allele distribution in parents of Down's syndrome children.
abstract: BACKGROUND
  An increased risk of Alzheimer's disease (AD) has been reported in young mothers of Down's syndrome (DS) probands. Allele epsilon4 of the apolipoprotein E (apoE) gene is a genetic susceptibility factor for AD. We examined the distribution of apoE alleles in people with DS and their parents.
  
  
  METHODS
  We studied 188 Danish people with non-mosaic free trisomy 21 of known parental origin (determined by DNA polymorphism analysis), and their parents, chosen from a population-based study of DS, and compared the frequency of apoE alleles with a previously published Danish control sample.
  
  
  RESULTS
  In people with DS, there was no significant difference in apoE allele distribution compared with controls. The frequency of allele epsilon4 in the fathers (11.8%) was significantly lower than in controls (17.4%, p=0.02). The frequency of allele epsilon4 in the mothers (19.4%) was not significantly different from that of controls. Nevertheless, in young mothers with a meiosis II error, epsilon4 frequency was 30.0%, significantly higher than in older mothers with a meiosis II error (13.0%, p=0.03).
  
  
  CONCLUSIONS
  We suggest that apoE allele epsilon4 is a risk factor for meiosis II non-disjunction in young mothers, but the biological role of apoE in oocytes remains to be investigated.
authors.affiliation: Department of Genetics, Institute of Child Health, Athens, Greece.
authors.forename: D
authors.initials: D
authors.lastname: Avramopoulos
authors.forename: M
authors.initials: M
authors.lastname: Mikkelsen
authors.forename: D
authors.initials: D
authors.lastname: Vassilopoulos
authors.forename: M
authors.initials: M
authors.lastname: Grigoriadou
authors.forename: M B
authors.initials: MB
authors.lastname: Petersen
mesh_terms: D000328:Adult; D000483:Alleles; D000544:Alzheimer Disease / Q000235:genetics*; D053327:Apolipoprotein E4; D001057:Apolipoproteins E / Q000235:genetics*; D016022:Case-Control Studies; D003718:Denmark / Q000453:epidemiology; D004314:Down Syndrome / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D008540:Meiosis; D009630:Nondisjunction, Genetic; D010331:Paternal Age; D011110:Polymorphism, Genetic; D012307:Risk Factors
chemical_list: D053327:Apolipoprotein E4; D001057:Apolipoproteins E