Humanity and human health: inextricable connection
I. Fundamentals of genetics: the alphabet of heredity
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Chromosomes: carriers of genetic information. The human genome, complex instructions for the construction and functioning of the body, is packed in 46 chromosomes organized in 23 pairs. Each couple consists of one chromosome inherited from the mother, and one from the father. Chromosomes consist of DNA (deoxyribonucleic acid), molecules that carry genetic instructions.
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DNA: Language Language. DNA has a double spiral structure resembling a screw staircase. The steps of this staircase are formed by four nitrogenous bases: adenine (A), Timin (T), guanine (G) and cytosine (C). The sequence of these bases determines the genetic code. A always connects to T, and G – C C.
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Genes: functional units of heredity. Genes are DNA areas encoding a synthesis of a certain protein or RNA. Proteins perform a variety of functions in the body, from catalysis of chemical reactions to the formation of structural components of cells. RNA (ribonucleic acid) is involved in the transmission of genetic information from DNA to ribosomes where protein synthesis occurs.
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Genom: a complete set of genetic information. The genome is a complete set of genetic information contained in the body of the body. It includes all genes, as well as non -dodging areas of DNA, which, as it turned out recently, play an important role in the regulation of genes activity.
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Mitosis and meiosis: processes of cellular division and inheritance. Mitosis is the process of dividing somatic cells (all cells of the body, except for the sexual), as a result of which two identical subsidiaries are formed, each of which contains a complete set of chromosomes (46). Meiosis is the process of dividing the germ cells (gametes – spermatozoa and eggs), as a result of which four subsidiaries are formed, each of which contains half a set of chromosomes (23). During fertilization, a fusion of a sperm and eggs are fused, restoring a complete set of chromosomes (46) in the zygote, the first cell of the new organism. Meiosis provides a genetic variety of offspring at the expense of two processes: crossingover (exchange of genetic material between homologous chromosomes) and independent discrepancy of chromosomes.
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Genotype and phenotype: the genetic constitution and its manifestation. The genotype is the genetic constitution of the body, that is, the totality of all its genes. A phenotype is a set of all the signs and characteristics of the body, which are the result of the interaction of the genotype and the environment. For example, the genotype determines the potential growth of a person, and the phenotype – the actual growth, which can be adjusted by nutrition and other environmental factors.
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Alleli: variants of the same gene. Alleles are various options for the same gene located in the same areas (loci) homologous chromosomes. For example, a gene that determines the color of the eyes can have alleles encoding brown or green.
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Dominant and recessive alleles: interaction of genes. The dominant allele is manifested in the phenotype even if it is present only in one copy (heterozygous condition). The recessive allele is manifested in the phenotype only if it is present in two copies (homozygous state). For example, if one of the parents handed over an allele that encodes brown eyes (dominant), and the other – an allele encoding the blue color of the eyes (recessive), then the child will have brown eyes. Blue eyes will only be if the child inherits the alleles of blue eyes from both parents.
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The laws of Mendel: the basic principles of inheritance of features. Gregor Mendel, the founder of genetics, formulated the three basic laws of inheritance of signs: the law of the uniformity of the first generation hybrids, the law of splitting signs and the law of independent inheritance of signs.
- The law of the uniformity of the first generation hybrids: When crossing two homozygous individuals that differ in one sign, all the first generation hybrids will be uniform and will have a phenotype determined by the dominant allele.
- The law of splitting signs: When crossing two heterozygous individuals in the offspring, there is a breakdown of signs in a certain ratio (usually 3: 1 for monohibride crossing).
- The law of independent inheritance of signs: Genes located in different chromosomes are inherited independently of each other.
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Mutations: changes in genetic information. Mutations are changes in the DNA sequence that can occur spontaneously or under the influence of mutagenes (environmental factors that cause mutations, such as radiation, chemicals). Mutations can be useful, neutral or harmful. Harmful mutations can lead to the development of genetic diseases.
II. Genetic diseases: the role of heredity in pathology
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Classification of genetic diseases. Genetic diseases can be classified according to various criteria, including the type of mutation (genetic, chromosomal, genomic), by inheritance (autosomal dominant, autosomal mining, linked to the floor) and type of affected organ or system.
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Gene diseases: mutations in separate genes. Gene diseases occur as a result of mutations in individual genes. Examples of gene diseases:
- Cykovyskidosis (cystic fibrosis): An autosomal recessive disease caused by a mutation in the CFTR gene, which encodes a protein that regulates the transport of chloride through cell membranes. This leads to the formation of thick mucus in the lungs, pancreas and other organs, causing breathing, digestion and reproductive function.
- Phenylketonuria (FCU): Autosomal recessive disease caused by a mutation in the PAH gene, which encodes the enzyme phenylalanine-hydroxylase, which is necessary for the metabolism of the phenylalanine amino acid. The accumulation of phenylalanine in the blood can lead to damage to the brain and mental retardation.
- Sickle -cell anemia: An autosomal recessive disease caused by a mutation in the HBB gene, which encodes beta-globin, a hemoglobin component. The mutation leads to the formation of abnormal hemoglobin, which deforms red blood cells, giving them a sickle form. These sickle cells are less elastic and can block blood vessels, causing pain, organs damage and anemia.
- Gentington disease: Autosomalum-dominant disease caused by a mutation in the HTT gene, which encodes the hydrocarpen of hydrofoil. The mutation leads to the progressive degeneration of nerve cells in the brain, causing involuntary movements, cognitive disorders and mental disorders.
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Chromosomal diseases: changes in the structure or number of chromosomes. Chromosomal diseases arise as a result of changes in the structure or number of chromosomes. Examples of chromosomal diseases:
- Down Syndrome (Trisomy 21): The disease caused by the presence of an additional copy of the 21st chromosome. This leads to mental retardation, characteristic features of the face, heart defects and other health problems.
- Turner syndrome (monosomy x): A disease that occurs only in women caused by the absence of one of the x chromosomes. This leads to low growth, infertility and other health problems.
- Klainfelter syndrome (XXY): A disease that occurs only in men caused by the presence of an additional X chromosome. This leads to high growth, infertility, gynecomastia (an increase in the chest glands) and other health problems.
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Genomic diseases: changes in the number of sets of chromosomes. Genomic diseases arise as a result of changes in the number of sets of chromosomes (for example, triploidia – the presence of three sets of chromosomes instead of two). Genomic diseases often lead to death in the early stages of development.
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Methods of inheritance of genetic diseases. Genetic diseases can be inherited by various methods:
- Autosomal dominant inheritance: The disease manifests itself in each generation, and it is enough to inherit only one copy of the mutant gene from one of the parents to get sick. The probability of transmitting the disease to the offspring is 50%if one of the parents is sick.
- Autosomal recessive inheritance: The disease is manifested only if two copies of the mutant gene are inherited, one from each parent. Parents are carriers of a mutant gene, but they themselves usually do not get sick. The probability of the birth of a sick child in two carrier parents is 25%.
- Inheritance The disease is associated with genes located on sex chromosomes (X or Y). Diseases linked to the X chromosome are more often found in men, since they have only one X chromosome. Women with two x chromosomes can be carriers of a mutant gene, without showing signs of the disease.
- Mitochondrial inheritance: The disease is transmitted only from mother to offspring, since mitochondria (organelles located in the cytoplasm of the cells and are responsible for the production of energy) are inherited only from the egg.
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Factors affecting the manifestation of genetic diseases. The manifestation of genetic diseases may depend on various factors, such as:
- Penetrance: The likelihood of a gene manifestation in individuals having this gene. Complete penetrance means that the gene manifests itself in all carriers, incomplete penetrance – that the gene manifests itself only in part of the carriers.
- Expressiveness: The severity of the sign determined by the genome. Various individuals with the same mutant gene can have a different degree of severity of the disease.
- Modifying genes: Other genes that can affect the expression of the main gene that defines the disease.
- Environmental factors: The diet, lifestyle, the effect of toxic substances and other environmental factors can affect the manifestation of genetic diseases.
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Diagnosis of genetic diseases. Diagnosis of genetic diseases may include various methods:
- Clinical examination and history of the anamnesis: Assessment of symptoms and family history of the disease.
- Laboratory research: A test of blood, urine, tissues for the detection of biochemical markers of the disease.
- Cytogenetic studies (karyotyping): Analysis of the chromosomal set for detecting chromosomal anomalies.
- Molecular genetic studies (DNA diagnostics): DNA analysis for identifying mutations in certain genes.
- The prenatal diagnostics: Diagnosis of genetic diseases in the fetus during pregnancy (for example, amniocentesis, choriona biopsy).
- Preimplantation genetic diagnostics (PGD): Diagnosis of genetic diseases in embryos obtained as a result of extracurporeal fertilization (IVF) before implantation into the uterus.
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Treatment of genetic diseases. Treatment of genetic diseases can be directed at:
- Relief of symptoms: The use of drugs, physiotherapy and other methods to relieve symptoms of the disease.
- Slow down the progression of the disease: The use of drugs and other methods to slow down the progression of the disease.
- Prevention of complications: Taking measures to prevent complications of the disease (for example, vaccination, diet).
- Gene therapy: The experimental treatment method aimed at correcting the mutant gene or the introduction of a functional copy of the gene into the cell.
- Feet -replacement therapy (ZFT): The introduction of an enzyme into the body, which is missing due to a genetic defect.
III. Hereditary predisposition to multifactorial diseases
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Multifact Diseases: the interaction of genes and the environment. Multifact diseases are diseases whose development is determined by the interaction of genetic predisposition and environmental factors. Examples of multifactorial diseases: cardiovascular diseases, diabetes, cancer, asthma, autoimmune diseases, mental disorders.
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The role of genes in the development of multifactorial diseases. A genetic predisposition to multifactorial diseases is determined by the presence of certain genetic options (polymorphisms) in genes that participate in the regulation of various physiological processes, such as immune response, metabolism, inflammation, etc. Each polymorphism makes a small contribution to increasing the risk of the development of the disease.
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Environmental factors affecting the development of multifactorial diseases. Environmental factors, such as diet, lifestyle, smoking, the effect of toxic substances, infections and stress, can have a significant impact on the development of multifactorial diseases. They can change the expression of genes (epigenetic changes) and enhance or weaken the genetic predisposition to the disease.
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Inheritance of multifactorial diseases. The inheritance of multifactorial diseases is complex and does not obey the simple laws of Mendel. The risk of developing the disease in relatives of the patient is higher than in the general population, but the exact risk depends on the number of genetic options that the individual inherited, and on the influence of environmental factors.
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Assessment of a genetic predisposition to multifactorial diseases. Assessment of a genetic predisposition to multifactorial diseases may include:
- History collection and family history analysis: Identification of cases of the disease in relatives.
- Genetic testing: DNA analysis for identifying genetic options associated with an increased risk of development of the disease. However, it should be borne in mind that genetic testing is not a diagnostic method and cannot predict whether a person will get sick in the future. It can only evaluate its genetic predisposition.
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Prevention of multifactorial diseases. Prevention of multifactorial diseases includes:
- Holding a healthy lifestyle: Proper nutrition, regular physical exercises, rejection of smoking and alcohol abuse.
- Avoiding the effects of toxic substances: Reducing the effects of contaminated air, water and food.
- Reducing stress levels: Using methods of relaxation and stress management.
- Regular medical examinations: Early diagnosis and treatment of diseases.
- Individualized recommendations: Development of individual prevention programs based on genetic predisposition and risk factors.
IV. Genetics and a healthy lifestyle: personalized medicine
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Personalized medicine: taking into account the genetic characteristics of the patient. Personalized medicine is an approach to the treatment and prevention of diseases, which takes into account the individual genetic characteristics of the patient, as well as environmental factors and lifestyle.
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Pharmacogenetics: the effect of genetics on the reaction to drugs. Pharmacogenetics studies the effect of genetic options on the body’s reaction to drugs. Some genetic options can affect the metabolism of drugs, their effectiveness and safety. Pharmacogenetic testing can help the doctor choose the most effective and safe drug for a particular patient.
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Nutrigenomy: the influence of genetics on the reaction to nutrition. Nutrigenomy studies the effect of genetic options on the body’s reaction on various foods and nutrients. Some genetic options can affect the metabolism of fats, carbohydrates and vitamins, as well as the risk of developing diseases associated with nutrition. Nutrichen testing can help develop an individual diet that will take into account the genetic characteristics of a person and help maintain health.
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Sportgenomic: the influence of genetics on sports achievements. Sportgenomics studies the influence of genetic options on sports achievements, such as strength, endurance and speed of recovery after training. Some genetic options may be associated with an increased risk of injuries. Sportsomic testing can help athletes develop an individual training program that will take into account their genetic features and reduce the risk of injuries.
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Ethical and social aspects of genetic testing. Genetic testing has important ethical and social aspects that must be taken into account:
- Confidentiality of genetic information: Protection of genetic information from unauthorized access.
- Discrimination based on genetic information: The inadmissibility of discrimination in the field of employment, insurance and other areas based on genetic information.
- Psychological consequences of genetic testing: The possibility of anxiety, depression and other psychological problems after obtaining the results of genetic testing.
- Reproductive solutions: The use of genetic information to make reproductive decisions (for example, pregnancy planning, prenatal diagnosis).
V. Conclusion
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VI. Resume
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VII. Conclusions
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