%0 Journal Article
%T Parental origin, nondisjunction, and recombination of the extra chromosome 21 in Down syndrome: a study in a sample of the Colombian population
%A Nelson Javier
%A Ram¨ªrez
%A Belalc¨¢zar
%A Helen Marcela
%A Yunis
%A Juan Jos¨¦
%A Quintero
%A Luis Napole¨®n
%A Arboleda
%A Gonzalo Humberto
%A Arboleda
%A Humberto
%J Biom¨¦dica
%D 2007
%I Instituto Nacional de Salud
%X introduction. free trisomy 21 is responsible for 95% of down syndrome cases. advanced maternal age and susceptible recombination patterns are recognized risk factors associated to down syndrome. maternal origin of trisomy occurs in approximately 90% of cases; paternal and mitotic origin share the remaining 10%. however, the recombination events that serve as a risk factors for trisomy 21 have not been carefully characterized. objective. to analyze and validate observations in a sample of colombian trysonomy 21 cases. materials and methods. twenty-two colombian families were selected, each with one affected down syndrome (free trisomy 21) child. microsatellite polymorphisms were used as dna markers to determine the parental/stage origin of non-disjunction and recombination events. non-parametric tests were used to compare our results with those reported. multiple correspondence analysis was used to outline different groups and their associations. results. distribution of trisomy 21 was 90.9% maternal, 4.5% paternal and 4.5% from mitotic origin, similar to distributions reported previously. however, we found differences in the frequency of maternal meiotic stage errors between the present study (46.1% meiosis i and 53.9% meiosis ii) compared to those reported previously (70% meiosis i and 30% meiosis ii). multiple correspondence analyses showed association of either local recombination events or absence of recombination with specific non-disjunction stages. conclusions. recombination patterns found in this study support the hypothesis that susceptible chiasmate configurations are associated to maternal meiosis i and meiosis ii errors. non-disjunction frequencies between maternal meiotic stages need to be clarified in our population.
%K down syndrome
%K nondisjunction
%K genetic
%K trisomy
%K meiosis
%K recombination
%K genetic
%K microsatellite repeats
%K s¨ªndrome de down
%K no disyunci¨®n gen¨¦tica
%K trisom¨ªa
%K meiosis
%K recombinaci¨®n gen¨¦tica
%K repeticiones de microsat¨¦lite..
%U http://www.scielo.org.co/scielo.php?script=sci_abstract&pid=S0120-41572007000100013&lng=en&nrm=iso&tlng=en