Researchers at Albert Einstein College of Medicine of Yeshiva University have discovered a potential explanation as to why older mothers face a greater risk for having offspring born with conditions characterized by abnormal chromosome numbers, such as Down syndrome. The results of this study appear in the journal Nature Communications.

Genetic data from over 4,200 families (each with at least two children) was obtained in collaboration with the company 23andMe to analyze the rate of recombination changes with parental age. More than 645,000 recombinations that had passed from parent to offspring were evaluated.

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The researchers found that the number of recombination events transmitted from mother to child increased with maternal age, although no such age-related effects were observed in fathers. They also discovered that more recombination events occur in close proximity to each other for older mothers. This greater rate of recombination in the chromosomes of older mothers could indicate that this tight regulation becomes weaker with age.

While these findings have not clinical application at this time, they could help scientists to better understand how aneuploidy or certain types of genetic mutation can occur through failures of recombination.

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