Eggs facilitate pregnancy by correcting sperm with genetic abnormalities

ABC Family



Eggs can correct genetic abnormalities in sperm and facilitate pregnancy, according to a study published by Italian researchers en la revista Fertility and Sterility. This capacity is closely linked to both the quality of the eggs and the severity of the damage to the DNA of the sperm.

Between 10% and 15% cases of infertility are caused by alterations of the genetic material of the sperm (DNA fragmentation). This kind of anomaly appears, often, in men with other seminal parameters (spermogram and spermocytogram) completely normal and can only be detected by specific tests.

Sperm DNA fragmentation is usually related to known causes such as advanced age, tobacco and drug abuse, occupational exposure to toxic substances, and local abnormalities of the male urogenital system (infection, varicocele). However, there are many where the cause is not easy to detect.. In addition, sperm DNA fragmentation is not necessarily linked to a general deterioration in their quality and quantity, reflected in the basic seminograms of men and in suspected cases it is necessary to perform a specific test to detect this condition.

How Eggs Correct DNA Errors

Errors produced by environmental factors occur frequently in any cell of the human body. To limit its effects, nature has developed different mechanisms for its correction. In the general rule, the affected cell first detects the problem and slows its own proliferation until the solution.

To detect and repair the defect, cells have several systems (cleavage of damaged parts of the DNA molecule, DNA component mismatch repair, non-homologous end junction repair, homologous recombination repair).

In the cells of the adult organism, these mechanisms are under the genetic control of each affected cell. After stopping its proliferation, the cell applies the most appropriate mechanisms to correct the defect. If it does not succeed, the cell activates the program of its own self-destruction (apoptosis) so as not to put the rest of the body at risk.

In the case of human embryos, which start their own genetic activity relatively late, 3 days after fertilization, protection against harmful effects of genetic errors contributed by sperm depends entirely on factors originating from the ovules. Hence the importance of the quality of the ovum at the time of being fertilized.

Common cause of infertility

Despite the availability of drug treatments to alleviate these abnormalities and laboratory methods to select sperm with normal DNA to fertilize eggs, sperm DNA fragmentation remains a frequent cause of assisted reproduction failures and abortions spontaneous.

The repairing capacity of the ovules was suggested three years ago by the research team of the MARGen clinic in Granada, led by Dr. Jan Tesarik and Dr. Raquel Mendoza-Tesarik, in a study in the journal Translational Andrology and Urology, in which it was pointed out that healthy eggs can correct genetic abnormalities in sperm after IVF (IVF) performed using the intracytoplasmic sperm injection (ICSI) technique and this hypothesis has just been confirmed by the Italian team.

According to doctors Jan Tesarik and Carmen Mendoza-Tesarik, “the most important thing is to carry out a thorough analysis of the clinical condition of both the man and his partner.” According to these specialists, the probability that the eggs correct the genetic abnormalities of the embryos is higher in young women “Although,” they point out, “today we have ovarian stimulation protocols capable of ‘rejuvenating’ the eggs and thus improving their repair capacity.”

The complete evaluation of the couple must include both the degree of genetic damage to the sperm and the repair capacity of the eggs, which is not always exactly related to the chronological age of the woman. «The key – according to these experts – is to choose the optimal treatment protocols for both to achieve the desired result: the birth of a healthy child. In the case of women, it is also very important to choose the appropriate treatment during ovarian stimulation ».


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