title: Altered patterns of multiple recombinant events are associated with nondisjunction of chromosome 21.
abstract: We have previously examined characteristics of maternal chromosomes 21 that exhibited a single recombination on 21q and proposed that certain recombination configurations are risk factors for either meiosis I (MI) or meiosis II (MII) nondisjunction. The primary goal of this analysis was to examine characteristics of maternal chromosomes 21 that exhibited multiple recombinant events on 21q to determine whether additional risk factors or mechanisms are suggested. In order to identify the origin (maternal or paternal) and stage (MI or MII) of the meiotic errors, as well as placement of recombination, we genotyped over 1,500 SNPs on 21q. Our analyses included 785 maternal MI errors, 87 of which exhibited two recombinations on 21q, and 283 maternal MII errors, 81 of which exhibited two recombinations on 21q. Among MI cases, the average location of the distal recombination was proximal to that of normally segregating chromosomes 21 (35.28 vs. 38.86 Mb), a different pattern than that seen for single events and one that suggests an association with genomic features. For MII errors, the most proximal recombination was closer to the centromere than that on normally segregating chromosomes 21 and this proximity was associated with increasing maternal age. This pattern is same as that seen among MII errors that exhibit only one recombination. These findings are important as they help us better understand mechanisms that may underlie both age-related and nonage-related meiotic chromosome mal-segregation.
authors.affiliation: Department of Human Genetics, Emory University School of Medicine, 615 Michael St, Suite 301, Whitehead Bldg, Atlanta, GA 30322, USA. trolive@emory.edu
authors.forename: Tiffany Renee
authors.initials: TR
authors.lastname: Oliver
authors.forename: Stuart W
authors.initials: SW
authors.lastname: Tinker
authors.forename: Emily Graves
authors.initials: EG
authors.lastname: Allen
authors.forename: Natasha
authors.initials: N
authors.lastname: Hollis
authors.forename: Adam E
authors.initials: AE
authors.lastname: Locke
authors.forename: Lora J H
authors.initials: LJ
authors.lastname: Bean
authors.forename: Reshmi
authors.initials: R
authors.lastname: Chowdhury
authors.forename: Ferdouse
authors.initials: F
authors.lastname: Begum
authors.forename: Mary
authors.initials: M
authors.lastname: Marazita
authors.forename: Vivian
authors.initials: V
authors.lastname: Cheung
authors.forename: Eleanor
authors.initials: E
authors.lastname: Feingold
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Sherman
mesh_terms: D002891:Chromosomes, Human, Pair 21 / Q000235:genetics*; D005260:Female; D005838:Genotype; D006801:Humans; D008423:Maternal Age; D008540:Meiosis; D009630:Nondisjunction, Genetic; D020641:Polymorphism, Single Nucleotide; D011995:Recombination, Genetic