title: Origin of trisomy 21 in Down syndrome cases from a Spanish population registry.
abstract: 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 Vallès (Spain). From 1991 to 1994, a higher prevalence of DS (22.7/10000 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.
authors.affiliation: Genetic's Laboratory, Corporació Sanitaria Parc Taulí, Parc Tauli, s/n, 08208, Sabadell, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Gómez
authors.forename: E
authors.initials: E
authors.lastname: Solsona
authors.forename: M
authors.initials: M
authors.lastname: Guitart
authors.forename: N
authors.initials: N
authors.lastname: Baena
authors.forename: E
authors.initials: E
authors.lastname: Gabau
authors.forename: J
authors.initials: J
authors.lastname: Egozcue
authors.forename: M R
authors.initials: MR
authors.lastname: Caballín
mesh_terms: D000028:Abortion, Induced; D000328:Adult; D002874:Chromosome Mapping; D002891:Chromosomes, Human, Pair 21; D000013:Congenital Abnormalities / Q000453:epidemiology / Q000235:genetics; D004314:Down Syndrome / Q000453:epidemiology* / Q000235:genetics*; D005260:Female; D005819:Genetic Markers; D018392:Genomic Imprinting; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D018895:Microsatellite Repeats; D011247:Pregnancy; D015995:Prevalence; D012042:Registries; D013030:Spain / Q000453:epidemiology
chemical_list: D005819:Genetic Markers