Aurora magazine

A Michigan Medicine study shows that the odds of having a boy or a girl are not 50/50. On the contrary, there are genes that favor the offspring of one sex or another, also determining their fertility. This at least in guinea pigs: other studies will be needed to see if this is also the case in humans.

The sex of the unborn child is determined by the X and Y chromosomes present in the gametes. The researchers examined the chromosomes of some guinea pigs and found genes related only to the X chromosomes. As they deepened, they identified multiple copies of the genes in question. In order to identify their role, they removed them from a group of guinea pigs using genetic editing techniques. Mice lacking copies of this gene family were more likely to have litters of males. In these cases, the ratio between males and females was around 60-40. Nevertheless, the percentage of sperm carrying the Y chromosome was always the same.

The difference was that the latter swam faster and more straight, gaining a considerable advantage over the other spermatozoa. After this first experiment, the team tried to increase the percentage of females. For this purpose, it has increased the number of copies of X-linked genes. In doing so, the percentage of female puppies has actually increased to 60%.

The family of genes discovered could therefore influence the velocity of sperm carrying this or that chromosome. But there is more. According to the study, the genes in question could also influence male fertility. In fact, by removing the copies of the gene, the researchers increased both the percentage of small males and the cases of infertility. The little ones without genes were in fact incapable of producing spermatozoa.

Source: med.umich.edu

Dr. David Liu led a study that led to the development of a new genetic editing technique, even more precise than Crispr-Cas9. Prime editing - that's the name - offers greater control and reduces the risk of unwanted changes. It could therefore open the door to new applications, today only theoretical in order to avoid unexpected changes in the DNA.

The new tool may fail to handle large changes like those of Crispr-Cas9. For the moment, therefore, it is unlikely to replace it in its entirety. This is because first editing encodes the changes on an RNA strand. The longer the filament stretches, the more likely it is to be ruined during the operation. On the other hand, the process is much more versatile than the old genetic editing technique.

Both Crispr-Cas9 and prime editing cut DNA at specific points in the genome. Crispr-Cas9 breaks both strands of the DNA double helix, after which it leaves the cell itself to repair the damage. This involves greater risks, since the healing process does not always go as planned. Prime editing bypasses these problems and reduces risks. The new technique uses Cas9 to recognize DNA sequences, but acts on a single strand of the helix. Then a second enzyme intervenes, guided by an RNA filament, which repairs the damage done by the cut. All this allows to act in a less invasive way and makes DNA healing better controllable.

Source: nature.com

An analysis published in the European Journal of Human Genetics proves that rare, even genetic, diseases are increasingly a priority. At least from the point of view of public health. Indeed, data collected by Orphanet estimates that between 3.5% and 5.9% of people suffer from rare diseases.

The data exclude tumors, viruses, bacteria and poisoning. Furthermore, they take into account only 67.6% of known rare diseases; this means that the data is at fault. Rare, genetic and non-genetic diseases are heterogeneous and distributed throughout the world. For many of these there is no cure and, in some cases, not even a real therapy.

They are largely chronic and often lead to death. Why? Because the researchers have very little epidemiological data on which to base the studies, which are therefore scarce. Not to mention that a lot of information comes from non-standardized sources, which makes it even more difficult to act efficiently and effectively.

The Orphanet database helps as much as possible. To date it contains more than 6,000 identified and classified rare diseases. About 71.9% of these are composed of rare genetic diseases, of which 69.9% occur at birth or in the earliest years. Despite the precociousness of symptoms, many families struggle to find a name for these diseases, which often remain without a diagnosis for years.

The prevalence of rare diseases is unbalanced: 149 pathologies affect about 80% of total patients, with 1-5 cases per 10,000 people. However, there are 241 pathologies that have a prevalence of 0.1-1 people per 10,000, with a percentage close to zero. These 400 diseases comprise 98% of total rare patients. All the others have a prevalence that is around 1 case per 1 million people. The study aims to bring out the many sick people who are still invisible today, who also represent a significant part of society.

Source: osservatoriomalattierare.it

Vasectomy is a surgical procedure that cuts or blocks the vas deferens, the channels that carry sperm from the testicles to the urethra. In this way the sperm is devoid of spermatozoa and ineffective for fertilization. It is an effective form of birth control, but is it really 100% safe? Spermatozoa have an average life of about 3 months.

Soon after the vasectomy, it is therefore possible that the seed is still fertile. During this time, analyzes are performed to ascertain that there are no more spermatozoa and that the sperm is "clean". Until then, it is good to continue using other types of contraceptives. Ignoring this waiting time is one of the main reasons for pregnancy after a vasectomy. It is not the only one. It happens that the procedure does not work and fails to block the ducts. If you perform the prescribed analyzes, identifying the problem quickly is easy enough. At this point, just repeat the whole thing.

It is much more difficult to identify the so-called recanalization. In this case, the ducts reform and create a new connection. In fact, the vasectomy is self-deprecating. This raises a last question: can the procedure be canceled? Most vasectomy operations are reversible. Nevertheless, only 3-6% of men retrace their steps. To cancel the effects of vasectomy, it is necessary to sew up the cut ducts or eliminate the blockage.

This solution is simpler and even more effective. Alternatively, it is possible to join a flap of ducts directly to the canal that carries sperm from the testicles. The procedure is more complex and has a lower success rate.

Source: medicalnewstoday.com