MALE INFERTILITY COULD BE HIDDEN IN DNA

The findings do not constitute a new diagnostic test or a cure for infertility. But they suggest that the conventional semen analysis may be revealing only part of a considerably more complex biological picture.

The male infertility There is a paradox that has been baffling doctors and patients for years. There are men whose semen analyses do not show enough abnormalities to explain why a couple is unable to conceive. Sperm are counted, their motility is studied, and their morphology is analyzed, but these variables do not necessarily provide all the information needed to determine their reproductive capacity.

A study published on September 25 in Human Reproduction He has sought that information in a different field: epigenetics.

The researchers studied sperm samples from 372 men in couples who were trying to conceive naturally. Instead of simply studying the genetic sequence, they analyzed DNA methylation, a chemical mechanism that can modify gene activity without altering the letters that make up the DNA itself.

To put it simply: two cells can contain virtually the same genetic instructions and yet use them differently. Part of that regulation depends on small chemical marks placed on the DNA. Methylation is one of them.

The scientists measured what they called epigenetic variability in sperm. And they found a significant association: the greater the abnormal variability in certain methylation patterns, the lower the couple’s fertility—that is, their probability of achieving a pregnancy during a given period.

The finding is particularly interesting because the study was not limited to patients undergoing assisted reproduction. The participants were couples who were trying to conceive naturally, which allows us to observe the phenomenon in a setting much closer to everyday reproduction. But the DNA The sperm is not the only place where scientists are looking for answers.

Another study released on September 25 draws attention to something that for a long time may have seemed to be merely the medium through which sperm travel: seminal plasma.

This fluid contains a wide variety of proteins, lipids, sugars, amino acids, hormones, and other molecules. A team from the University of Aveiro in Portugal conducted a systematic review of 20 studies that had compared the metabolism of seminal plasma in fertile and infertile men. The goal was to find a kind of chemical signature of infertility.

The researchers observed recurrent alterations in various molecules and metabolic pathways related to functions essential to sperm, including energy production, oxidative stress, and the metabolism of lipids and amino acids.

This opens up an interesting possibility: in the future, a semen sample could provide much more information than a simple sperm count.

Instead of asking only how many sperm cells there are and how they move, it might also be possible to study the biochemical environment in which they live and the molecular changes associated with certain types of infertility.

This idea is particularly relevant in so-called idiopathic cases—those in which infertility is present but no clear cause can be identified. Recent research using metabolomics, microRNA, and other molecular techniques is beginning to reveal differences between the seminal plasma of fertile men and that of patients with unexplained infertility.

However, there is a significant gap between identifying a molecular association and developing a medical test.

Scientists still need to confirm these patterns in larger populations, determine which abnormalities cause infertility and which are simply consequences of other processes, and verify whether these biomarkers can reliably predict who will have difficulty conceiving.

The same is true of the epigenetic study published in Human Reproduction. The fact that a link has been found between variability in sperm DNA methylation and a lower probability of pregnancy does not mean that an epigenetic test capable of diagnosing an individual man’s fertility already exists. However, both studies point in the same direction.

For a long time, we have studied sperm primarily from the outside: their number, shape, and movement. Now, research is beginning to delve into their DNA, the chemical signals that regulate that DNA, and the molecular world surrounding it.

And that is where some of the answers that the microscope could never reveal to us might be hidden.