A study conducted at the University of Florence that analyzed the chromosome by detecting the anomalies associated with azoospermia arrived at this hypothesis.
According to the World Health Organization, in Western countries, infertile couples are 15%. Male infertility accounts for about half of the cases (7%) and for almost half of men there is no medical explanation as to why it has a low or no sperm count. Now an international study, published onAmerican Journal of Human Geneticshas highlighted how they could originally exist mutations of 55 genes on the X chromosome, one of the two sex chromosomes. The team of researchers from five Centers coordinated by Csilla Krauszassociate professor of Endocrinology at the University of Florence and andrologist at the Careggi University Hospital.
I study
We conducted genetic analyzes on a sample of 2,354 men, from all over Europe and of different ages and ethnicities, all of them idiopathic azoosperms: they had, therefore, few spermatozoa in seminal fluid, less than 10 thousand per milliliter of semen, but there was no known cause – explains Professor Krausz who is also president of the European Academy of Andrology, the first woman to fill this role – . The results obtained from the analyzes were compared with those of 209 men with a normal sperm count, up to 200 million per milliliter. We focused on those X chromosome genes that were recurrently mutated in more than one patient and in more than one study cohort. We have located 21 mutated genes strongly associated and 34 moderately associated with absent or poor sperm production.
How much does the X chromosome matter
Often the X chromosome is identified as the female one, because women have two copies while men have one. For the first time, we have studied all the genes (more than 850) of the X chromosome, the least investigated, discovering how it is also very important for human reproduction – Krausz specifies -. Until now, research on male infertility had mainly focused on mutations of the other sex chromosome present in men, the Y
, the one that determines the male sex; on the X, however, only three genes with clinical significance in azoospermia were known. Our investigation, in addition to confirming their role, has greatly increased the number of X-linked genes to be studied in case of severe impairment of sperm production.
Perspectives
The importance of the discovery, which took place by studying a considerable sample in the field of andrological genetics, consists inincrease the chances of giving a response to the patient who does not know the cause of his azoospermia. Identifying which genes, once mutated, cause the complete absence of spermatozoa not only in the seminal fluid, but also in the testicle, opens up the possibility of having genetic tests which in addition to finding the cause would also give indications for the selection of patients not to be subjected to testicular biopsyan invasive procedure.
The cause note
Male infertility can depend on three factors. The first hormonal endocrine regulation, which occurs when certain hormones essential to stimulate the production of sperm and testosterone are missing or deficient. This relatively rare condition, it concerns 5-10% of cases, it can be congenital or acquired for a tumor, for example, at the level of the brain or pituitary which reduces the presence of these hormones. The second factor can be the so-called primitive testicular problems: they represent the main cause, about 75% of cases of male infertility.
They can be of genetic or acquired origin, such as after inflammation, infection, trauma or failure of the testicle to descend. Another cause of infertility are i post testicular problems: The testicle works, but the ducts that carry the sperm out are blocked or have not developed. The treatments are different, ranging from hormonal therapies to surgery, to assisted fertilization, concludes the expert.
July 21, 2022 (change July 21, 2022 | 12:19)
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