Genetic Causes of Infertility in Men
Genetic Causes of Infertility in Men
More than 10-15% of Iranian couples suffer from infertility, and in about half of the cases, infertility is caused by quantitative and qualitative defects in the various stages of sperm production and transmission.
Infertility in men has a variety of causes, including infectious diseases such as mumps, congenital or acquired structural disorders of the genital system such as varicocele, autoimmune diseases, genetic disorders, hormonal disorders, environmental factors such as frequent contact with heat or heavy metals, and common dementia. He called it impotence and premature ejaculation.
Genetic disorders, including mutations or chromosomal defects, account for more than 30% of cases of infertility in men.
These disorders can cause sperm loss, decreased sperm count, impaired sperm motility, and abnormal sperm morphology.
For example, chromosomal displacements and anoploids (disorders of a number of chromosomes) can cause infertility or recurrent miscarriages.
Numerous genetic causes can cause infertility in men, the most important of which are listed below:
Chromosomal Disorders:
1. Klein-Felter syndrome (47XXY): This syndrome is the most common chromosomal disorder in infertile men.
Symptoms include small, hard testicles, azoospermia, gynecomastia, and androgen-related symptoms.
These patients are often tall, and some have varying degrees of mental retardation.
However, this disorder occurs in mosaic individuals with varying degrees of oligospermia.
Structural Disorders of Chromosomes: The prevalence of this group of disorders in infertile men is 5 to 10 times that of other individuals due to the disruption of the natural structure of chromosomal tetrads during gametogenesis in meiosis.
Of course, some of these people produce sperm; But most of their sperm contain unbalanced chromosomal abnormalities, and there is a high risk of miscarriage or the birth of a baby with a congenital anomaly if pregnancy occurs.
3- 45X / 46XY mosaicism: These people suffer from gonadal dysgenesis, decrease in spermatogenesis level and decrease in normal sperm.
Y chromosome long arm microdispersions:
The Y chromosome is a submetacentric chromosome, and on its long arm are identified three main areas called AZF (azoospermic factor) including AZFb, AZFa, and AZFc, which are involved in sexual development and spermatogenesis, and any removal in these areas is associated with infertility. .
The frequency of AZF microsurgery in men with oligospermia is 7%, and this rate reaches 10% with the selection of azoospermic individuals.
Also, in many cases of idiopathic infertility, microsurgery is observed in the Yq (long arm of the Y chromosome).
The location and size of the microstructure is directly related to the type and severity of the disorder.
The main significance of the molecular study of the presence of microsurgery in AZF is that many of these individuals can have children using assisted reproductive techniques; But the sons of men who have been removed from the AZF will inherit the disorder.
In some cases, this removal is more common in children and is accompanied by sexual ambiguity. Of course, most of the minor issues in the Y chromosome are new.
Multiplex-PCR method is used on this chromosome to study the molecular elimination of Yq.
Other causes:
Numerous single disorders can be associated with infertility, some of which are mentioned:
1- Congenital lack of ductal ducts: Defranicular ducts are not formed in these people; Therefore, although there is sperm in their testicles, these sperm cannot come out with semen.
Approximately one-fourth of people with congenital sciatica (CBAVD) have some degree of cystic fibrosis (CF); Therefore, it is recommended to check for mutations in the CFTR gene in all patients with CBAVD.
The spouse should also be evaluated for mutations in the CFTR gene before using assisted reproductive techniques in these patients.
2. Cartagena Syndrome: This genetic syndrome includes infertility caused by sperm immobility and respiratory disorders caused by a protein deficiency called Dynein.
This protein is one of the building blocks of sperm tail and mucous membranes of the respiratory tract.
3- Myotonic muscular dystrophy: This syndrome is characterized by muscle degeneration, myotonia, cataracts, diabetes, and testicular atrophy in the third to fourth decade of life.
Androgen deficiency and gynecomastia are seen in only a small number of patients.
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Tips for triploidy
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A Brief Overview of Sexual Chromosome Disorders
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Lessons from Microdeletion syndromes
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Overview of common chromosomal abnormalities (Down syndrome, Edward syndrome, and Patau syndrome)
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Tips on basic concepts in chromosomal abnormalities
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An overview of "Fragile X syndrome"
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Tips for carrier screening testing for latent genetic diseases
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A review of the diagnostic test for amniocentesis during pregnancy
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A review of the applications of genetic counseling in medicine
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Paternity Test