Origin of trisomy 21 in Down syndrome cases from a Spanish population registry

David Gómez, Eulàlia Solsona, Miriam Guitart, Neus Baena, Elisabeth Gabau, Josep Egozcue, M. Rosa Caballín

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19 Citations (Scopus)


We have carried out a population-based study on the origin of the extra chromosome 21 in 38 families with Down syndrome (DS) offspring in El Valles (Spain). From 1991 to 1994, a higher prevalence of DS (22.7/10,000 live births, stillbirths and induced abortions) was found compared to the majority of EUROCAT registries. The distribution of trisomy 21 by origin was 88% maternal (90.6% meiosis I, 6.2% meiosis II, 3.1% maternal mosaicism), 5.6% paternal (50% meiosis I, 50% meiosis II) and 5.6% mitotic. The percentage of parental mosaicism was 2.7%. These percentages are similar to those previously reported. Recombination study revealed a maternal meiosis I genetic map of 32.68 cM (approximately one-half the length of the normal female map). Mean maternal age among non-recombinant cases involving MI errors was significantly lower (31.1 years) than among those cases showing one observable crossover (36.1 years) (P < 0.05); this could support the hypothesis that 'achiasmate' chromosomes may be subject to aberrant segregation regardless of maternal age. (C) 2000 Editions scientifiques et medicales Elsevier SAS.
Original languageEnglish
Pages (from-to)23-28
JournalAnnales de Genetique
Publication statusPublished - 1 Jan 2000


  • DNA polymorphism analyses
  • Down's syndrome
  • Mosaicism
  • Non-disjunction
  • Recombination


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