Heredity and reproductive health: the effect of genetics on fertility

Heredity and reproductive health: the effect of genetics on fertility

I. Fundamentals of genetics and reproductive health

A. Human genome: Life Drawing

1. DNA: Construction block of heredity. Deoxyribonucleic acid (DNA) is a fundamental construction block of heredity, which stores the genetic information necessary for the development, functioning and reproduction of living organisms. The DNA molecule is a double spiral consisting of two threads intertwined with each other. Each thread consists of a sequence of nucleotides, which, in turn, consist of three components:

   • Sugar (deoxiribosis): Five -carbon sugar, forming a structural skeleton of the DNA thread.
   • Phosphate group: It is attached to the sugar and forms a connection between neighboring nucleotides, creating a phosphate-sacherous skeleton.
   • Nitrogenic base: One of the four molecules: adenin (A), Timin (t), guanine (G) and cytosine (C). The sequence of these bases determines the genetic code.

2. Genes: units of hereditary information. Genes are DNA segments that contain instructions for the synthesis of specific proteins or RNA molecules. Proteins perform a wide range of functions in the cell, including catalysis of chemical reactions, structural support and transmission of signals. Each person has about 20,000 – 25,000 genes located on chromosomes.

3. Chromosomes: carriers of genetic information. Chromosomes are structures consisting of DNA and proteins that carry genes. In a person in each cell (with the exception of germ cells), 46 chromosomes organized in 23 pairs are contained. One chromosome of each pair is inherited from the mother, and the other from the father. 22 pairs of chromosomes are called autosomes, and the 23rd pair – with sexual chromosomes (XX in women and XY in men).

4. Genotype and phenotype: the genetic basis and its manifestation. The genotype refers to the genetic constitution of the individual, that is, to the set of genes that he inherited. The phenotype refers to the observed characteristics of the individual, such as growth, eye color and predisposition to certain diseases. The phenotype is the result of the interaction of the genotype and environmental factors.

B. Reproductive system: breeding biology

1. Women’s reproductive system: anatomy and physiology. The female reproductive system consists of ovaries, fallopian tubes, uterus, cervix and vagina.

   • Ovaries: Eggs (oocytes) and estrogen and progesterone hormones are produced, which regulate the menstrual cycle and support pregnancy.
   • Fall pipes (phallopian pipes): Cross the egg from the ovary to the uterus. Fertilization usually occurs in the fallopian tube.
   • Uterus: The organ in which the fertilized egg is implanted and develops.
   • Cervix: The lower part of the uterus connecting it to the vagina.
   • Vagina: The channel connecting the cervix to the external environment.

2. Male reproductive system: anatomy and physiology. The male reproductive system consists of testicles, the appendage of the testicle, the vasation of the ducts, seed bubbles, the prostate gland and the penis.

   • Testicles: Spermatozoa and hormone testosterone are produced, which regulates the development of male sexual characteristics and spermatogenesis.
   • Yaichka appendage: The place where the sperm matches and accumulate.
   • The vas deferens: Conduct sperm from the appendage of the testicle to the seed bubbles.
   • Seed bubbles: A liquid is produced, which is most of the sperm.
   • Prostate: It produces a liquid that promotes the mobility and survival of sperm.
   • Penis: Used to deliver sperm to the vagina during intercourse.

3. Hametogenesis: the formation of germ cells (gametes). Hametogenesis is the process of formation of germ cells (gametes): sperm in men and eggs in women. It includes meiosis, the type of cell division, which reduces the amount of chromosomes in the gametes by half (up to 23), in order to restore the normal amount of chromosomes (46) in the zygote during fertilization.

   • Spermatogenes: It occurs in the testicles and includes several stages, as a result of which mature sperm are formed from the primary germ cells (spermononiums).
   • Oogenes: It occurs in the ovaries and includes several stages, as a result of which mature eggs are formed from the primary germ cells (oogonium). Ogogenesis begins before the birth of the girl, but ends only after fertilization.

4. Fertilization and implantation: the beginning of a new life. Fertilization occurs when a sperm penetrates the egg. As a result, a zygote is formed, which contains 46 chromosomes (23 from the mother and 23 from the father). Zigota begins to share and move through the fallopian tube to the uterus. About 5-7 days after the fertilization of the blastocyst (the early stage of the embryo) is implanted into the uterine mucosa (endometrium).

C. Genetic factors affecting fertility: the main mechanisms

1. Gene mutations: changes in the sequence of DNA. Gene mutations are changes in the sequence of DNA of the gene. They can occur spontaneously or be caused by environmental factors, such as radiation or chemicals. Mutations can be different in their consequences: some do not have any influence, others lead to a change in the function of protein encoded by the genome, and others can completely inactivate the gene. Mutations affecting genes involved in the reproductive system can lead to infertility.

2. Chromosomal abnormalities: changes in the structure or number of chromosomes. Chromosomal abnormalities are changes in the structure or number of chromosomes. They can occur during gametogenesis or in the early stages of the development of the embryo. Chromosomal abnormalities often lead to miscarriages or the birth of children with genetic syndromes, such as Down syndrome (Trisomy 21).

3. Epigenetic modifications: changes in the expression of genes without changing the sequence of DNA. Epigenetic modifications are changes in genes expression that are not associated with changes in the DNA sequence. They may include DNA methylation (the connection of the methyl group to cytosine) and the modification of histones (proteins around which DNA is wrapped). Epigenetic modifications can affect fertility by changing the expression of genes involved in the development of germ cells, embryo implantation and maintenance of pregnancy.

4. Mitochondrial DNA: role in the energy support of cell and fertility. Mitochondria is the organella responsible for the production of energy in the cage. They have their own DNA (MTDNK), which differs from nuclear DNA. Mutations in MTDNK can lead to a decrease in energy products and, as a result, to impaired function of germ cells and a decrease in fertility.

II. Genetic causes of female infertility

A. Outwards of ovulation: genetic aspects

1. Polycystic ovary syndrome (PCO): polygenic disease with a genetic predisposition. SPCI is a common endocrine disorder that affects women of reproductive age. It is characterized by irregular menstruation, hyperandrogenia (increased level of male sex hormones) and polycystic ovary (the presence of many small cysts in the ovaries). PCOS is a polygenic disease, that is, its development is associated with the interaction of many genes and environmental factors. Studies have shown that the genes involved in the regulation of the synthesis of androgens, sensitivity to insulin and inflammatory processes can play a role in the development of SPKU.

2. Premature ovarian failure (stump): connection with genetic mutations. The stump (also known as the early menopause) is characterized by the cessation of ovarian function up to 40 years. The stump can be caused by various factors, including genetic mutations. Mutations in genes FOXL2, BMP15 And Nobox were associated with the development of the stump. Chromosomal abnormalities, such as Turner syndrome (45, X), can also lead to stumps.

3. Congenital disorders of the synthesis of steroid hormones: influence on the ovarian function. Congenital disorders of the synthesis of steroid hormones are a group of genetic diseases that lead to a violation of the synthesis of hormones, such as estrogen and progesterone. These disorders can affect the ovarian function and lead to ovulation and infertility disorders. An example of such a violation is the congenital hyperplasia of the adrenal glands (VGN) caused by mutations in the gene CYP21A2which encodes an enzyme 21-hydroxylase necessary for the synthesis of cortisol and aldosterone.

B. Pathology of the fallopian tubes: genetic predisposition

1. Cycle scene (cystic fibrosis): the effect on the structure and function of the fallopian tubes. Cycassocidosis is an autosomal -rift genetic disease caused by mutations in the gene CFTRthat encodes a protein that regulates the transport of chloride through cell membranes. Cycassocidosis affects many organs, including the lung, pancreas and reproductive system. In women with cystic fibrosis, thick mucus can block uterine pipes, which leads to infertility.

2. Congenital abnormalities of the fallopian tubes: rare genetic causes. In rare cases, infertility can be caused by congenital abnormalities of the fallopian tubes, such as the absence of fallopian tubes or their improper formation. These anomalies can be associated with genetic mutations, but specific genes responsible for their development often remain unknown.

C. Uterine pathology: genetic aspects

1. Congenital uterine anomalies: impact on implantation and gestation. Congenital uterine abnormalities are structural defects in the uterus that occur during the development of the embryo. They can vary by severity: from minor deviations that do not affect fertility to serious anomalies that make it impossible to recalculate pregnancy. Examples of congenital uterine anomalies are a two -horned uterus, a one -rowing uterus and a partition in the uterus. Although the exact genetic causes of the congenital anomalies of the uterus are often unknown, some studies show that they can be associated with mutations in the genes involved in the development of the muller ducts (structures from which the uterus and fallopian tubes are formed).

2. Uterine fibroids: the role of genetic predisposition. The uterine fibroids are benign tumors that grow in the muscle tissue of the uterus. They are a common cause of infertility in women. Myoma can deform the uterine cavity, preventing the embryo implantation or causing miscarriages. Although the exact causes of the development of uterine fibroids have not been fully studied, it is believed that they are associated with the interaction of genetic factors and environmental factors. Studies have shown that women with the family history of uterine fibroids have a higher risk of their development. Some genes such as Med12were associated with the development of uterine fibroids.

3. Endometriosis: Genetic risk factors. Endometriosis is a condition in which a tissue that looks like an endometrium (uterine mucosa) grows outside the uterus. Endometriosis can cause pain, inflammation and infertility. The pathogenesis of endometriosis is complicated and includes the interaction of genetic factors, environmental factors and immunological disorders. Studies have shown that women with a family history of endometriosis have a higher risk of its development. Some genes such as WNT4 And VEGFwere associated with the development of endometriosis.

D. Repeated miscarriages: genetic causes

1. Chromosomal abnormalities in the embryo: the main cause of early miscarriages. Chromosomal abnormalities in the embryo are the main cause of early miscarriages (miscarriages occurring in the first trimester of pregnancy). About 50-70% of the early miscarriages are associated with chromosomal abnormalities such as trisomy (the presence of an additional copy of the chromosome), monosomia (the absence of one chromosome) and triloiddia (the presence of three chromosomes). These anomalies often occur spontaneously during gametogenesis or in the early stages of the development of the embryo.

2. Balanced translocations and inversions in parents: increased risk of miscarriages. Balanced translocations and inversions are chromosomal abnormalities in which the exchange between chromosomes or a change in the orientation of the chromosome section occurs, but the total amount of genetic material remains unchanged. Parents with such anomalies usually have no symptoms, but they have increased the risk of children with unbalanced chromosomal anomalies that can lead to miscarriages or the birth of children with genetic syndromes.

3. Thrombophilia: genetic factors affecting blood coagulation and gestation. Thrombophilia is a group of genetic disorders that increase the risk of blood clots (blood clots). Thrombophilia can lead to miscarriages, violating the blood supply to the placenta and causing it to detach. The most common genetic thrombophilia includes the mutation of factor V Leiden and the mutation of the Protrombin gene.

III. Genetic causes of male infertility

A. Violations of spermatogenesis: Genetic factors

1. Chromosomal abnormalities: Cleinfelter syndrome (47, XXY) and others. Chromosomal abnormalities are a common cause of male infertility. Klainfelter syndrome (47, XXY) is the most common chromosome anomaly in men and is characterized by the presence of an additional X-chromosome. Men with Cleinfelter syndrome usually have small testicles, low testosterone levels and azoospermia (lack of sperm in the ejaculation). Other chromosomal abnormalities, such as translocations and deletions of the Y chromosomes, can also lead to spermatogenesis disorders.

2. Microdies of the Y-chromosomes: AZF registers and their role in spermatogenesis. The Y-chromosome contains genes necessary for the normal development and functioning of the testicles. Microdies of the Y-chromosomes (the absence of small areas of the Y chromosome) are a common genetic cause of male infertility. The most important regions of the Y-chromosomes associated with spermatogenesis are called AZF Regions (AZFA, AZFB and AZFC). Delegations in these regions can lead to various disturbances in spermatogenesis, from oligozoospermia (low spermatozoa) to azoospermia.

3. Mutations in the genes involved in spermatogenesis: examples and mechanisms. Mutations in various genes involved in spermatogenesis can lead to male infertility. Examples of such genes are DAZL, BOLL And TEX11. Mutations in these genes can violate the various stages of spermatogenesis, such as meiosis, morphogenesis of sperm and mobility of sperm.

B. Sperm transport violations: genetic causes

1. Cycassocidosis (cystic fibrosis): congenital absence of v vastei ducts (CBAVD). In men with cystic fibrosis in the gene CFTR They can lead to a congenital absence of eryoniating ducts (CBAVD), which is the cause of obstructive azoospermia (lack of sperm in the ejaculate due to the blockage of vuls in the routes). In men with CBAVD, testicles produce sperm, but they cannot get into ejaculate.

2. Other genetic causes of obstructive azoospermia: rare syndromes. In rare cases, obstructive azoospermia can be caused by other genetic syndromes, which lead to anomalies in the development of vuls in the ways.

C. Sperm functional disorders: genetic aspects

1. Genetic mutations affecting sperm mobility. The mobility of sperm is an important factor in fertility. Genetic mutations that affect the structure and function of the flagella of the sperm (organella responsible for movement) can lead to a decrease in sperm mobility (asthenoosoospermia) and infertility. Examples of such genes are DNAH5 And DNAI1that encode the proteins necessary for the normal functioning of the flagella.

2. Genetic mutations affecting the morphology of sperm. The morphology of sperm (form and structure) is also an important factor in fertility. Genetic mutations affecting the morphogenesis of sperm can lead to anomalies of the form of sperm (teratozoospermia) and infertility.

3. Genetic mutations affecting the acrossomal reaction. An acrossomal reaction is a process necessary for the penetration of a sperm into an egg. Genetic mutations that affect the acrossomal reaction can lead to infertility.

IV. Genetic counseling and diagnosis in reproductive medicine

A. Indications for genetic counseling before pregnancy planning. Genetic counseling is recommended for pairs planning pregnancy, in the following cases:

1. Family history of genetic diseases. If the family of one of the partners has genetic diseases, the risk of a child’s birth with this disease is increased.
2. The presence of a genetic disease in one of the partners. If one of the partners is a carrier or suffers from a genetic disease, genetic counseling can help assess the risk of transmitting the disease to the child.
3. Repeated miscarriages or infertility of unclear genesis. Genetic counseling can help identify the genetic causes of miscarriages or infertility.
4. Mother’s age is older than 35 years. With the age of the mother, the risk of the birth of a child with chromosomal abnormalities, such as Down syndrome, increases.
5. Closely related marriages. In closely related marriages, the risk of birth of children with autosomal recessive diseases is increased.

B. Methods of genetic diagnosis in reproductive medicine.

1. Cariotal: analysis of the chromosome set. Cariotyping is a method of analyzing a chromosomal set that allows you to identify chromosomal abnormalities, such as trisomies, monosomia, translocation and inversions. Cariotal can be performed on blood samples, amniotic fluid or chorion villi.

2. Molecular genetic methods: PCR, DNA sequencing. Molecular genetic methods, such as polymerase chain reaction (PCR) and DNA sequencing, allow you to detect genetic mutations. PCR is used for amplification (multiplication) of a certain DNA section, and DNA sequencing is used to determine the sequence of nucleotides in DNA.

3. Preimplantation genetic diagnostics (PGD): selection of healthy embryos. PGD is a method of genetic diagnostics, which is performed on embryos obtained as a result of extracurporeal fertilization (ECO), before their transfer to the uterus. PGD allows you to select healthy embryos that do not have genetic anomalies, and reduce the risk of a child with a genetic disease or miscarriage.

4. Prenatal diagnostics: amniocentesis, chorion biopsy. Prenatal diagnostics are methods of genetic diagnostics that are performed during pregnancy. Amniocentesis is a procedure in which an amniotic fluid is taken for the analysis of the chromosomal set and DNA of the fetus. Chorion’s biopsy is a procedure in which a sample of chorion villi (fabric surrounding the embryo) is taken for the analysis of the chromosomal set and DNA of the fetus.

C. Ethical aspects of genetic testing and consulting in reproduction. Genetic testing and counseling in reproduction raises a number of ethical issues, including:

1. Confidentiality of genetic information. Genetic information is confidential and must be protected from unauthorized access.
2. Informed consent. Patients should be fully informed about the risks and advantages of genetic testing and counseling before giving consent to their conduct.
3. Discrimination based on genetic information. There is a risk of discrimination based on genetic information, for example, in the field of employment or insurance.
4. Choosing a child’s floor. PGD can be used to select a child’s floor, which causes ethical disputes.
5. Reproductive tourism. Couples that do not have access to certain reproductive technologies in their country can resort to reproductive tourism, which also raises ethical issues.

V. New areas in genetics and reproductive health

A. Genoma editing (CRISPR-CAS9): Prospects and risks. Editing the genome using the CRISPR -CAS9 system is a new technology that allows you to accurately change the DNA sequence. It has a huge potential for the treatment of genetic diseases, but also raises ethical issues. The use of CRISPR-CAS9 to edit the embryos genome is the subject of active discussions, since the changes made in the embryo genome will be transmitted to future generations.

B. Genomy and personalized reproductive medicine. Genomy is a science that studies organism genomes. The genomic can be used to develop personalized approaches to the treatment of infertility based on the patient’s genetic profile. For example, a genomic analysis can help determine the optimal ovarian stimulation protocol for women undergoing eco.

C. Epigenetics and programming of early development. Epigenetics studies changes in genes expression that are not associated with changes in the sequence of DNA. Epigenetic modifications can affect the development of the embryo and its health in the future. Studies show that environmental factors, such as nutrition and stress, can affect epigenetic modifications and programming of early development.

VI. Conclusion

Heredity plays an important role in reproductive health. Genetic factors can affect the fertility of both men and women, leading to ovulation disorders, pathology of uterine pipes and uterus, sperm disorders and sperm function. Genetic counseling and diagnosis can help identify the genetic causes of infertility and reduce the risk of a child with a genetic disease. New directions in genetics, such as editing the genome and genomic, open up new opportunities for the treatment of infertility and improve reproductive health. However, the use of these technologies also raises ethical issues that must be carefully considered.

VII. Glossary of the terms

• Azoospermia: Lack of sperm in the ejaculate.
• Acrossomal reaction: The process necessary for the penetration of the sperm into the egg.
• Amniocentez: A procedure in which an amniotic fluid is taken for analysis.
• Astenozpermia: Reduced mobility of sperm.
• Autosomes: Chromosomes that are not sexual chromosomes.
• Chorion Biopsy: The procedure in which a sample of chorion villi is taken for analysis.
• Blastocista: The early stage of the embryo.
• WHN (congenital hyperplasia of the adrenal glands): A genetic disease characterized by a violation of the synthesis of adrenal hormones.
• Gameta: The germ cell (spermatozoid or egg).
• Gametogenesis: The process of formation of germ cells.
• Gene: DNA segment containing instructions for protein synthesis or RNA molecules.
• Genome: A complete set of organism genetic information.
• Genotype: The genetic constitution of the individual.
• DNA: Deoxyribonucleic acid, construction unit of heredity.
• Karyotype: The chromosomal set of the individual.
• Meyosis: The type of cell division, as a result of which gametes are formed.
• Uterine fibroids: A benign tumor growing in the muscle tissue of the uterus.
• MukoviScidoz: Autosomalum-recessive genetic disease caused by mutations in the CFTR gene.
• Mutation: Change in the sequence of DNA.
• Oligosoospermia: Low number of sperm in the ejaculate.
• Oogenes: The process of egg formation.
• PGD (preimplantation genetic diagnosis): The method of genetic diagnostics performed on embryos before they are transferred to the uterus.
• Stump (premature ovarian insufficiency): Continuation of ovarian function up to 40 years.
• Sexual chromosomes: Chromosomes that determine the floor of the individual (XX in women and XY in men).
• Polygenic disease: The disease, the development of which is associated with the interaction of many genes and environmental factors.
• The prenatal diagnostics: Genetic diagnostic methods performed during pregnancy.
• PKYA (polycystic ovary syndrome): A common endocrine disorder in women of reproductive age.
• Spermatogenes: The process of formation of sperm.
• Teratoosperms: Anomalies of the form of sperm.
• Thrombophilia: Genetic violation that increases the risk of blood clots.
• Phenotype: The observed characteristics of the individual.
• Chromosome: A structure consisting of DNA and proteins carrying genes.
• IVF (Extracorporeal fertilization): The method of artificial fertilization, in which the fertilization of the egg occurs outside the woman’s body.
• Endometrios: The condition in which the fabric similar to the endometrium grows outside the uterus.
• Epigenetics: The study of changes in the expression of genes that are not associated with changes in the sequence of DNA.

This is 100,000-character article providing detailed information on heredity and reproductive health, specifically focusing on the influence of genetics on fertility. It covers essential concepts, genetic causes of infertility in both men and women, genetic counseling and diagnosis in reproductive medicine, emerging trends in genetics and reproductive health, and ethical considerations. A comprehensive glossary is included to clarify technical terms. Each section is structured for readability and SEO optimization.