Missed connections: recombination and human aneuploidy

The physical exchange of DNA between homologs, crossing‐over, is essential to orchestrate the unique, reductional first meiotic division (MI). In females, the events of meiotic recombination that serve to tether homologs and facilitate their disjunction at MI occur during fetal development, preceding the MI division by several decades in our species. Data from studies in humans and mice demonstrate that placement of recombination sites during fetal development influences the likelihood of an MI nondisjunction event that results in the production of an aneuploid egg. Here we briefly summarize what we know about the relationship between aneuploidy and meiotic recombination and important considerations for the future of human assisted reproduction. Key Points What's already known about this topic? Aneuploidy is the most common chromosome abnormality in humans. Aneuploidy is associated with errors in meiotic recombination. What does this study add? This review summarizes results of studies of trisomic pregnancies, fetal oocytes and adult oocytes, demonstrating links between recombination errors and nondisjunction.