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International study shows: Our body prevents mutations of specific genetic information in egg cells

Francesca Chiaromonte, professor of statistics at the Sant'Anna School of Advanced Studies in Pisa, contributed to the study, which was published in the journal Science Advances

Publication date: 08.08.2025
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Mutations in mitochondrial DNA (mtDNA) present in oocytes do not increase with age. This is the main finding of an important international study published in the journal Science Advances, conducted by the Johannes Kepler University in Linz (Austria) and Pennsylvania State University (USA), in collaboration with a number of international partners, including the Sant'Anna School of Advanced Studies in Pisa, the only Italian institution involved in the research. At a time when many women are having children later in life, and mutations generally tend to occur more frequently, this research shows that even in pregnancies of older women, the risks associated with the accumulation of mtDNA mutations in oocytes do not increase.

"Not only did the number of mutations in mtDNA remain consistently low, but there are also indications that the body actively eliminates certain mutations," explains Barbara Arbeithuber, first author of the study at JKU in Linz. The body therefore appears to actively protect this particular genetic information.

Mitochondria are the powerhouses of cells. They have their own DNA (mtDNA), which is passed from the mother to the child. The study used a highly accurate sequencing technique – Duplex Sequencing – which made it possible to identify even the rarest mutations and distinguish them precisely from sequencing errors common in less advanced techniques.

The results show that although the number of mutations increases with age in other tissues such as blood and saliva, mtDNA remains stable over time in oocytes. Furthermore, potentially harmful mutations are less frequent in the functionally important regions of the mitochondrial genome, suggesting a natural selection and protection mechanism.


The contribution of the Sant'Anna School of Advanced Studies to the study

The Scuola Superiore Sant'Anna in Pisa participated in the study thanks to the contribution of Francesca Chiaromonte, professor of Statistics. Chiaromonte participated in the design of the statistical analyses used in the research. ‘In this as in other studies in the field of genetics and genomics, the use of appropriate statistical models and techniques is essential for extracting information from sequencing data,’ explains Chiaromonte.