An unprecedented cause of male infertility has been discovered by a team of scientists from the University of Newcastle in the United Kingdom. It is estimated that around 7% of men are affected by infertility problems. According to the definition of the World Health Organization, male infertility is defined as a disease of the reproductive system in which there is an inability to conceive after 12 or more months of regular sexual life without the use of contraceptives. In different couples, in 50% of cases, fertility problems are due to disorders in the male’s reproductive functions. In addition, in about half of cases of male infertility, the cause remains unexplained. So far, the genes responsible for this problem have been known. These genes have been found to be recessive – they must be passed down from both the mother and father to be activated. But scientists from the University of Newcastle have discovered a new genetic mechanism that completely changes the theories. 29 new mutations identified There are many causes of male infertility and about 15% of those we know of are genetic in origin. Genetic causes account for much of the more severe cases of infertility and reduced seminal fluid production, explains Professor Joris Veltman, dean of the Institute of Biological Sciences at the University of Newcastle in the UK. This time, the identified mutations were not inherited from the mother and father. Experts have discovered that these DNA changes occur during the reproduction process, when the DNA of both parents is replicated. Errors then occur in the replication of genes that are later responsible for spermatogenesis. This can lead to infertility in men who carry these mutations. In the study, 185 DNA samples were collected from patients diagnosed with infertility and their parents. All genes carried by these patients and their parents were studied and 145 new mutations were identified. 29 of these are associated with genes known to play an important role in male reproduction. Therefore, mutations in these genes can seriously alter their expression and lead to infertility. It is currently impossible to know the exact effect of these mutations on spermogenesis. Identifying the role of each requires further work. What is certain is that these mutations may underlie the causes of male infertility in the same family. These patients could successfully produce offspring using assisted reproduction, but the risk of passing on the mutations to the offspring is high. These mutations cause dominant forms of male infertility, unlike the other genes identified so far, which are recessive. Therefore, there is a 1:2 chance that a man will pass this mutation on to his sons. Thus, each generation will have to turn to assisted reproduction methods and treatments to be able to produce offspring.We currently do not know how many people are affected by these mutations, nor what proportion of infertility cases are due to this newly discovered cause. In any case, this is a total paradigm shift for infertile couples, giving them new opportunities. The study was published in the journal Nature Communications. Sources: https://www.sciencesetavenir.fr/sante/grossesse/decouverte-d-une-nouvelle-cause-d-infertilite-masculine_160768 https://www.nature.com/articles/s41467-021-27132-8