How age-related genetic anomalies contribute to the maternal age effect
For women in their 30s and beyond, the probability of a pregnancy that results in a miscarriage or a Down syndrome pregnancy is staggering with the risk increasing to 1 in 3 by the time a woman reaches her early 40s due to the "maternal age effect," the high incidence of mistakes in chromosome segregation that occur during the cell division process of meiosis, which gives rise to the egg. Now, in a study just published online in the PNAS (Proceedings of the National Academy of Sciences), Dartmouth researchers have provided the first evidence in an intact living organism that an increase of reactive oxygen species (ROS) within oocytes (the cells that undergo meiosis to form eggs) causes a significant increase in meiotic chromosome segregation errors.