Obligate Short-Arm Exchange in De Novo Robertsonian Translocation Formation Influences Placement of Crossovers in Chromosome 21 Nondisjunction
AUTOR(ES)
Berend, Sue Ann
FONTE
The American Society of Human Genetics
RESUMO
Robertsonian translocations (ROBs) involving chromosome 21 are found in ∼5% of patients with Down syndrome (DS). The most common nonhomologous ROB in DS is rob(14q21q). Aberrant recombination is associated with nondisjunction (NDJ) leading to trisomy 21. Haplotype analysis of 23 patients with DS and de novo rob(14q21q) showed that all translocations and all nondisjoined chromosomes 21 were maternally derived. Meiosis II NDJ occurred in 21 of 23 families. For these, a ROB DS chromosome 21 genetic map was constructed and compared to a normal female map and a published trisomy 21 map derived from meiosis II NDJ. The location of exchanges differed significantly from both maps, with a significant shift to a more distal interval in the ROB DS map. The shift may perturb segregation, leading to the meiosis II NDJ in this study, and is further evidence for crossover interference. More importantly, because the event in the short arms that forms the de novo ROB influences the placement of chiasmata in the long arm, it is most likely that the translocation formation occurs through a recombination pathway in meiosis. Additionally, we have demonstrated that events that occur in meiosis I can influence events, such as chromatid segregation in meiosis II, many decades later.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=379241Documentos Relacionados
- Diagnosis and treatment of the short-arm type posterior semicircular canal BPPV
- A giant short arm of no. 21 chromosome in mother of 21/21 translocation mongol.
- Translocation of chromosome 4 and 9 with ring formation of chromosome 4 short arm.
- Parental Origin and Timing of De Novo Robertsonian Translocation Formation
- Nondisjunction Rates and Abnormal Embryonic Development in a Mouse Cross between Heterozygotes Carrying a (7, 18) Robertsonian Translocation Chromosome