New Study Finds Human Egg Cells Are Shielded From Age-Related Genetic Mutations

As humans age, it is well understood that most cells in the body accumulate genetic mutations, contributing to age-related diseases and overall biological aging. However, recent research published in Science Advances reveals a surprising exception: human egg cells, or oocytes, appear to be protected from age-related increases in mitochondrial DNA (mtDNA) mutations. Mitochondria, often called the cell's powerhouses, contain their own DNA, and mutations here can lead to serious health issues such as Leigh Syndrome, which affects motor skills and heart function.

In this groundbreaking study, scientists analyzed mitochondrial DNA from 80 individual oocytes obtained from 22 women aged between 20 and 42 years. They also examined mitochondrial DNA variations in the women’s blood and saliva. While it was observed that mutations in mitochondrial DNA increased with age in blood and saliva cells, the same was not true for oocytes. This suggests that an evolutionary mechanism might actively protect female egg cells from accumulating harmful genetic mutations over time.

Further, the study found that the few mutations present in oocytes mainly occurred in non-coding regions of mtDNA, regions that do not produce proteins. Conversely, mutations in the protein-coding regions, which could potentially disrupt mitochondrial function, were significantly less frequent. This selective protection could have significant implications for reproductive health, especially as women tend to delay childbirth.

Contrary to prior assumptions that older mothers may transmit more mitochondrial mutations, the research indicates that the risk of passing on age-related mtDNA mutations from oocytes might be lower than previously thought. However, the researchers caution that the study’s small sample size and limited focus mean these findings are preliminary and do not cover the full reproductive lifespan.

Overall, this study provides new insights into the resilience of human egg cells against genetic mutations associated with aging, potentially easing concerns about genetic risks from delayed motherhood and informing future reproductive counseling. Source: ScienceX.