MOUNTAIN VIEW, Calif., Feb. 25, 2015 — Researchers at Albert Einstein College of Medicine of Yeshiva University and 23andMe., Inc. have found possible clues to why older mothers face a higher risk for having children born with Down syndrome, and other conditions characterized by abnormal chromosome numbers.
Published in the journalNature Communications, the study looked specifically at a process called recombination, which occurs during cell division. During recombination, chromosomes from parents are shuffled to create a unique combination of genetic traits. It is during this process that errors in our genetic code can occur, and be passed down to children during reproduction. For example, children may inherit chromosomes with rearrangements or an abnormal number of chromosomes.
The study looked at patterns of recombination among more than 4,200 families who are 23andMe customers* and consented to participate in research. All told, the researchers examined more than 645,000 recombination events.
The study showed that the normal process by which parental chromosomes are recombined before they are passed onto children appears to be less regulated as women age. Researchers also verified that the number of recombination events transmitted from mother to child increases with maternal age.
Further, researchers found that the spacing between recombination events occurring on the same chromosome becomes less constrained as women age. For older mothers, more recombination events occur in close proximity to one another. No such age-related effects were observed in fathers.
“Knowing more about how recombination changes with parental age and how that may affect genetic mutations provides clues that merit further study,” said the paper’s lead author Adam Auton, Ph.D., assistant professor of genetics and of epidemiology & population health at Einstein.
“This study has led to greater insights into one of the fundamental biological processes that helps drive human evolution,” said 23andMe statistical geneticist Nick Furlotte, one of the paper’s co-authors. “This research is also a great example of how the ability to study massive genetic and phenotypic data sets at scale can lead to insights into a variety of biological phenomenon.”
Full paper citation and availability:“Escape from crossover interference increases with maternal age.”
In addition to Auton and Furlotte, the other authors are: Christopher L. Campbell, a Ph.D. student at Einstein; Nick Eriksson, and David Hinds, affiliated with 23andMe.
*Data was contributed by 23andMe customers who provided informed consent to take part in this research under a protocol approved by the AAHRPP-accredited institutional review board, Ethical and Independent Review Services.