American researchers found that women carrying the mutated kinesin protein KIF18A in the genes produced a greater number of abnormal eggs, leading to early natural terminations of pregnancy.
- Variants in kinesin genes, particularly the KIF18A protein, contribute to the increase in aneuploid eggs, i.e. those with an abnormal number of chromosomes.
- Additionally, this mutated protein accelerates the reproductive aging process and decreases fertility.
- According to the authors, these results lay the foundation for non-invasive biomarkers for egg quality, a first step towards personalized fertility medicine.
The reproductive lifespan of women is highly dependent on the quality of the eggs. Indeed, miscarriages are often caused by the fact that women produce aneuploid eggs, that is to say those with an abnormal number of chromosomes, and this possibility increases with age. Issue : “knowledge of the precise genetic landscape underlying oocyte abnormalities in women is limited, as data on the subject are difficult to obtain and therefore absent from public genetic datasets”according to scientists at Rutgers University in New Brunswick (United States).
Women with abnormal eggs have a KIF18A genetic mutation
In a recent study, published in the journal Proceedings of the National Academy of Sciences (PNAS)the latter wanted to identify the genetic determinants of reproductive aging via oocyte aneuploidy in women. To do this, they first carried out a complete computer analysis of the genes of people with high embryonic aneuploidy. Next, the team reviewed data from a biobank from an in vitro fertilization clinic and looked for patterns in maternal DNA sequences collected from patients.
“We identified 404 genes carrying variants enriched in adults with pathologically high oocyte aneuploidy levels,” said the authors. An analysis implicated genes for the kinesin protein family in egg aneuploidy. According to the results, a variant, which differs from the non-mutated version by only one amino acid, in the gene for the kinesin protein KIF18A was identified. This mutated protein accelerates the aging process of eggs in young women carrying the variant, which ultimately reduces their fertility.
Pregnancy and genetic anomalies: less risk at 28 than at 32
To confirm these results, scientists conducted experiments on rodents modified to contain the genetic variant. These showed that the animals produced more abnormal eggs at an earlier age than normal. “If you know your genetic risk, you will know that your results will be better if you start at 28 rather than 32. This can make a huge difference in your success,” declared Leelabati Biswaswho participated in the research.
“We can say that this is not just a correlation, but a cause and effect relationship. The results allowed us to strongly validate our computational data. This is a first step “We are moving in a direction where we may be able to give women more opportunities for precision medicine, to better inform them, using targeted genetic information for reproductive treatments.” she added.
