Genetics and health: how heredity affects our life
Section 1: Fundamentals of genetics and heredity
1.1. DNA: Drawing of life
DNA (deoxyribonucleic acid) is a molecule containing genetic instructions necessary for the development, functioning and reproduction of all known living organisms and many viruses. This is a fundamental construction unit of heredity. DNA consists of two chains twisted into a spiral forming a double spiral. Each chain consists of nucleotides, and each nucleotide contains sugar (deoxyribose), a phosphate group and nitrogen base. There are four types of nitrogenous bases: adenine (A), Timin (t), guanine (G) and cytosine (C). The order of these grounds determines the genetic code.
1.1.1. DNA structure: double spiral
Double DNA spiral is a brilliant engineering solution of nature. Firstly, it provides protection for genetic information, placing it inside the spiral structure. Secondly, it allows you to easily copy DNA when dividing cells. The pairs of bases (A C T, and G C C) are connected by hydrogen bonds, which ensures the stability of the spiral. The rupture of these hydrogen bonds allows you to expand DNA and copy each chain.
1.1.2. DNA replication: copying life
DNA replication is a process through which DNA doubles so that each subsidiary receives a complete set of genetic information. This process is extremely accurate, but sometimes mistakes nevertheless happen, which leads to mutations. DNA replication occurs in several stages with the participation of many enzymes, such as DNA polymerase.
1.2. Genes: units of heredity
The gene is a DNA section containing instructions for the synthesis of a particular protein. Proteins, in turn, perform many functions in the body, from the construction of tissues to the regulation of chemical reactions. Genes are units of heredity that are transmitted from parents to offspring.
1.2.1. Genes expression: from gene to squirrel
Gene expression is a process by which information encoded in the gene is used to synthesize a functional product, usually protein. This process includes two main stages: transcription and broadcast. Transcription is the process of copying DNA into RNA (ribonucleic acid). Broadcast is the process of using RNA for protein synthesis.
1.2.2. Genes regulation: expression control
Genes regulation are a process by which the cell controls what genes are expressed, and to what extent. Genes regulation are necessary for the development, differentiation of cells and adaptation to the environment. There are various mechanisms of genes regulation, such as epigenetic modifications and binding of transcription factors with DNA.
1.3. Chromosomes: Packed DNA
Chromosomes are structures consisting of DNA and proteins that carry genes. A person has 23 pairs of chromosomes, 22 pairs by autosomes and one pair of sex chromosomes (XX in women, XY in men). Chromosomes become visible during cell division.
1.3.1. Cariotic: chromosomal set
A karyotype is an orderly arrangement of a chromosomes of a cell. Analysis of the Kariotip can detect chromosomal abnormalities, such as trisomies (the presence of additional chromosome) or monosomia (lack of chromosome).
1.3.2. Mitosis and meiosis: cell division
Mitosis is a process of dividing cells, as a result of which two subsidiaries are formed with an identical set of chromosomes. Meiosis is a process of division of cells, as a result of which gametes (spermatozoa and eggs) with a half set of chromosomes are formed. Meiosis includes recombination, the process of exchanging genetic material between chromosomes, which leads to a genetic diversity.
1.4. Heredity: transmission of genetic information
Heredity is the transfer of genetic information from parents to offspring. The principles of heredity were first formulated by Gregor Mendel, who studied the inheritance of signs of peas.
1.4.1. Mendel laws: dominance, segregation, independent inheritance
Mendel formulated three basic laws of heredity: the law of dominance, the law of segregation and the law of independent inheritance. The law of dominance states that in the presence of two different alleles (gene variants), one allele can dominate the other and determine the phenotype (observed characteristics). The law of segregation states that gene alleles are divided during the formation of gametes, so that each gameta receives only one allele. The law of independent inheritance states that the alleles of different genes are inherited independently of each other.
1.4.2. Genotype and phenotype: genetic code and its manifestation
The genotype is the genetic constitution of the body, that is, a set of alleles that it carries. The phenotype is the observed characteristics of the body, which are the result of the interaction of the genotype and the environment.
1.5. Mutations: a source of genetic diversity
Mutations are changes in the DNA sequence. Mutations can occur spontaneously or be caused by the influence of mutagenes, such as radiation or chemicals. Mutations can be harmful, neutral or useful. Useful mutations can contribute to the adaptation of the body to the environment.
1.5.1. Types of mutations: point mutations, deletions, inserts, translocations
There are several types of mutations, including spot mutations (changes in one nucleotide), deletions (removal of the DNA section), insert (DNA insertion) and translocation (moving the DNA section from one place to another).
1.5.2. The value of mutations: evolution and disease
Mutations are a source of genetic diversity and underlie evolution. However, mutations can also cause diseases.
Section 2: Hereditary Diseases
2.1. Classification of hereditary diseases
Hereditary diseases are diseases caused by mutations in genes or chromosomal abnormalities. They can be transmitted from parents to offspring. Hereditary diseases can be classified according to the type of inheritance, according to the gene or chromosome in which a mutation occurred, or according to the system of organs that affects the disease.
2.1.1. Monogenic diseases: violation of one gene
Monogenic diseases are caused by mutations in one gene. They are inherited according to the simple laws of Mendel. Examples of monogenic diseases include cystic fibrosis, sickle cell anemia and phenylketonuria.
2.1.2. Polygenic diseases: the influence of several genes
Polygenic diseases are caused by the interaction of several genes and environmental factors. They are inherited in a more complex way than monogenic diseases. Examples of polygenic diseases include cardiovascular diseases, diabetes and cancer.
2.1.3. Chromosomal abnormalities: a change in the number or structure of chromosomes
Chromosomal abnormalities occur when the number or structure of chromosomes changes. They can occur spontaneously or be caused by the influence of mutagenes. Examples of chromosomal abnormalities include Down syndrome (Trisomy 21), Turner syndrome (monosomy X) and Klyinfelter syndrome (XXY).
2.2. Types of inheritance
The type of inheritance defines how a hereditary disease is transmitted from parents to offspring.
2.2.1. Autosomal dominant inheritance
With autosomal dominant inheritance, one copy of the mutant gene is enough to cause a disease. Sick children usually have at least one sick parent. Examples of autosomal dominant diseases include hydrophoreton disease and neurofibromatosis.
2.2.2. Autosomalist inheritance
With autosomal recessive inheritance, two copies of the mutant gene are necessary to cause a disease. Sick children usually have healthy carrier parents, each of which carries one copy of the mutant gene. Examples of autosomal recessive diseases include cystic fibrosis and sickle cell anemia.
2.2.3. X-linked dominant inheritance
With X-linked dominant inheritance, one copy of the mutant gene on the X chromosome is enough to cause the disease. In women, the disease can be less pronounced than in men, since they have two x chromosomes.
2.2.4. X-linked recessive inheritance
With a X-linked recessive inheritance, two copies of the mutant gene on the X chromosome are necessary to cause disease in women. In men, one copy of the mutant gene on the X chromosome is enough. Therefore, men are more likely to suffer from x-linked recessive diseases. Examples of X-linked recessive diseases include hemophilia and colortonism.
2.2.5. Mitochondrial inheritance
Mitochondria is an organella containing its own DNA. Mitochondrial diseases are inherited from the mother, as spermatozoa do not bring mitochondria into the zygote.
2.3. Examples of common hereditary diseases
2.3.1. Cystic fibrosis
Cystic fibrosis is an autosomal-rose-free disease caused by mutations in the CFTR gene, which encodes a protein that regulates the transport of chloride through cell membranes. Cystic fibrosis affects the lungs, pancreas, intestines and other organs.
2.3.2. Sickle -cell anemia
Sickle-cell anemia is an autosomal recessive disease caused by a mutation in the HBB gene, which encodes beta-Globin, a component of hemoglobin. Sickle -cell anemia leads to the formation of anomalous hemoglobin, which causes expanding red blood cells, making them sickle.
2.3.3. Gentington disease
Gentington disease is an autosomal dominant disease caused by a mutation in the HTT gene, which encodes the HuntingTin protein. Gentington disease leads to progressive degeneration of neurons in the brain.
2.3.4. Down syndrome
Down syndrome is a chromosomal anomaly caused by the presence of an additional copy of the chromosome 21 (trisomy 21). Down syndrome is characterized by mental retardation, characteristic features of the face and other health problems.
2.3.5. Phenylketonuria (FKU)
FCU is an autosomal recessive metabolic disorder caused by a deficiency of the enzyme phenylalain nyxydroxylasis (PAG). Phag is necessary for the splitting of the phenylalanine amino acid. Without treatment, FCU can lead to mental retardation.
2.4. Genetic counseling
Genetic counseling is a process by which experts help people and families understand and adapt to the medical, psychological and family consequences of genetic diseases. Genetic counseling can help evaluate the risk of the disease, choose methods of diagnosis and treatment, and make reasonable decisions on family planning.
2.4.1. Indications for genetic counseling
Indications for genetic counseling include the presence of hereditary diseases in the family, infertility, repeated miscarriages, the birth of a child with congenital defects, as well as a desire to undergo genetic testing.
2.4.2. Stages of genetic counseling
Genetic counseling usually includes a history of anamnesis, risk assessment, genetic testing (if necessary), interpretation of results and providing information about possible treatment and management options.
Section 3: The role of heredity in the development of diseases
3.1. Hereditary predisposition
Hereditary predisposition is an increased risk of developing the disease due to genetic factors. The presence of a hereditary predisposition does not mean that a person will necessarily get sick, but increases the likelihood of developing the disease when exposed to certain environmental factors.
3.1.1. Genes polymorphisms and the risk of diseases
Genes polymorphisms are common genes that can affect the risk of developing diseases. Some genes polymorphisms can increase the risk of developing certain diseases, while others can reduce risk.
3.1.2. Interaction of genes and the environment
The development of many diseases depends on the interaction of genes and the environment. The genetic predisposition can be enhanced or weakened by the influence of environmental factors, such as diet, lifestyle and the effect of toxins.
3.2. Cancer and heredity
Cancer is a group of diseases characterized by uncontrolled growth and the spread of abnormal cells. Although most cases of cancer are not hereditary, about 5-10% of cancer are associated with hereditary mutations.
3.2.1. Hereditary forms of cancer
Hereditary forms of cancer arise due to mutations in genes that control the growth and division of cells. These mutations can be transmitted from parents to offspring, increasing the risk of developing cancer in the family. Examples of hereditary forms of cancer include hereditary breast cancer and ovaries (BRCA1 and BRCA2), hereditary colorectal cancer (linch syndrome) and hereditary melanoma.
3.2.2. Genetic testing for a predisposition to cancer
Genetic testing for a predisposition to cancer can help identify people with an increased risk of cancer. This can allow them to take preventive measures, such as a more frequent examination and preventive operations.
3.3. Cardiovascular diseases and heredity
Cardiovascular diseases (SVD) are a group of diseases that affect the heart and blood vessels. Heredity plays an important role in the development of the CVD.
3.3.1. Hereditary risk factors of the SSZ
Hereditary risk factors of the SSZ include increased cholesterol, high blood pressure, diabetes and obesity. Genetic factors can also affect the risk of atherosclerosis, thrombosis and arrhythmias.
3.3.2. Family hypercholesterolemia
Family hypercholesterolemia is a hereditary disease characterized by a high level of cholesterol in the blood. It is caused by mutations in genes that control cholesterol metabolism. Family hypercholesterolemia increases the risk of developing early SVDs.
3.4. Diabetes and heredity
Diabetes is a group of metabolic diseases characterized by a high level of glucose in the blood. Heredity plays an important role in the development of both type 1 diabetes and type 2 diabetes.
3.4.1. Type 1 diabetes and genetic predisposition
Type 1 diabetes is an autoimmune disease in which the body’s immune system attacks and destroys pancreatic cells that produce insulin. Genetic predisposition plays an important role in the development of type 1 diabetes. Some genes, such as HLA genes, increase the risk of type 1 diabetes.
3.4.2. Type 2 diabetes and polygenic inheritance
Type 2 diabetes is a disease in which the body cannot effectively use insulin. Type 2 diabetes is a polygenic disease, that is, several genes and environmental factors affect its development.
3.5. Neuropsychic diseases and heredity
Many neuropsychic diseases have a hereditary component.
3.5.1. Schizophrenia and bipolar disorder
Schizophrenia and bipolar disorder are serious mental illness, which are characterized by impaired thinking, perception and mood. Heredity plays an important role in the development of these diseases.
3.5.2. Alzheimer’s disease and heredity
Alzheimer’s disease is a neurodegenerative disease that leads to a progressive deterioration in cognitive functions. Heredity plays an important role in the development of Alzheimer’s disease, especially the early form of the disease.
Section 4: Genetic testing and its use in medicine
4.1. Types of genetic testing
Genetic testing is an analysis of DNA, RNA or chromosomes to detect genetic variations associated with diseases. There are several types of genetic testing that are used for various purposes.
4.1.1. Diagnostic testing
Diagnostic testing is used to confirm the diagnosis of a hereditary disease in a person with symptoms.
4.1.2. Premptomatic testing
Presumptomatic testing is used to detect genetic mutations that cause diseases that develop at a later age, such as hydrofoil disease.
4.1.3. Prenatal testing
Prenatal testing is used to detect genetic anomalies in the fetus during pregnancy.
4.1.4. Screening of newborns
Newborns screening is used to identify hereditary diseases in newborns, which can be treated in the early stages.
4.1.5. Pharmacogenetic testing
Pharmacogenetic testing is used to determine how a person will respond to medicines.
4.2. Genetic testing methods
4.2.1. DNA sequencing
DNA sequencing is a method for determining the sequence of nucleotides in DNA. DNA sequencing can be used to identify mutations in genes.
4.2.2. PCR (polymerase chain reaction)
PCR is a method of amplification (multiplication) of a certain DNA section. PCR is used to increase the amount of DNA so that it can be easier to detect.
4.2.3. Fish (fluorescent hybridization in situ)
Fish is a method of visualization of chromosomes and genes using fluorescent probes. Fish is used to detect chromosomal abnormalities.
4.2.4. Analysis of microuines
Analysis of microuines is a method that is used to simultaneously analyze the expression of thousands of genes. Analysis of microuines can be used to identify changes in the expression of genes associated with diseases.
4.3. Ethical and social aspects of genetic testing
Genetic testing raises a number of ethical and social issues.
4.3.1. Confidentiality and discrimination
The results of genetic testing should be confidential. People should not be discriminated against their genetic data.
4.3.2. Informed consent
People should give informed consent to genetic testing. They should be informed about the risks and advantages of testing, as well as how the results will be used.
4.3.3. The availability of genetic testing
Genetic testing should be accessible to everyone who needs it, regardless of their socio-economic status.
Section 5: Gene therapy and other methods of treating hereditary diseases
5.1. Gene therapy
Gene therapy is a method of treating hereditary diseases by introducing genes into the patient’s cells. Gene therapy can be used to replace a defective gene with a functional genome for inactivation of a defective gene or to introduce a gene that encodes a protein that can help in the treatment of the disease.
5.1.1. Types of genetic therapy
There are several types of genetic therapy, including genetic therapy in vivo (genes are introduced directly into the patient’s body) and gene therapy ex vivo (cells are extracted from the patient’s body, genes are introduced into the cells in the laboratory, and then the cells return to the patient’s body).
5.1.2. Gene therapy vectors
Genes are introduced into cells using vectors. Vectors can be viral or non -viral. Viral vectors are more effective, but can cause an immune response.
5.1.3. Examples of genetic therapy
Gene therapy is used to treat a number of hereditary diseases, including spinal muscle atrophy, beta-talassemia and leukemia.
5.2. Genes editing
Genes editing is a method that allows you to accurately change the sequence of DNA in the cells. CRISPR-CAS9 is a powerful technology for editing genes, which allows scientists to cut DNA in a certain place and insert, delete or replace the genes.
5.2.1. CRISPR-CAS9
CRISPR-CAS9 is a system consisting of CAS9 protein and RNA guide. RNA guide is associated with a certain DNA section, and CAS9 protein cuts DNA in this place.
5.2.2. Application of genes editing
Genes can be used to treat hereditary diseases, cancer and infectious diseases.
5.2.3. Ethical aspects of genes editing
Genes editing a number of ethical issues, especially with regard to editing germ cells (sperm and eggs), since the changes will be transmitted to future generations.
5.3. Other methods of treating hereditary diseases
5.3.1. Replacement therapy
Replacing therapy is used to replace the missing protein or enzyme. For example, replacement enzyme therapy is used to treat Gosher’s disease.
5.3.2. Organs and tissue transplantation
Transplantation of organs and tissues can be used to replace a damaged organ or tissue. For example, bone marrow transplantation can be used to treat sickle cell anemia.
5.3.3. Supporting therapy
Supporting therapy is used to alleviate the symptoms of the disease and improve the quality of the patient. For example, physiotherapy can be used to improve mobility in patients with cystic fibrosis.
Section 6: Epigenetics: heredity outside the genes
6.1. What is epigenetics?
Epigenetics is the study of hereditary changes in the expression of genes, which are not associated with changes in the sequence of DNA. Epigenetic changes can be caused by environmental factors, such as diet, stress and the effects of toxins.
6.2. Epigenetic mechanisms
6.2.1. DNA methylation
DNA methylation is the addition of a methyl group to DNA. DNA methylation usually suppresses genes.
6.2.2. Modifications of histones
Histons are proteins around which DNA is wrapped. Histonian modifications can affect the expression of genes. Some modifications of histones activate the expression of genes, while others suppress it.
6.2.3. Microorno
Microrm is small RNA molecules that regulate the expression of genes.
6.3. The role of epigenetics in the development of diseases
Epigenetic changes play an important role in the development of many diseases, including cancer, cardiovascular diseases, diabetes and neuropsychic diseases.
6.4. Epigenetics and diet
Diet can affect epigenetic changes. Some nutrients, such as folic acid and vitamin B12, are necessary for DNA methylation.
6.5. Epigenetics and lifestyle
A way of life, such as smoking and drinking alcohol, can affect epigenetic changes.
Section 7: The Future of Genetics and Health
7.1. Personalized medicine
Personalized medicine is an approach to treatment, which takes into account the genetic characteristics of a person. Genetic testing can be used to select the most effective treatment for a particular patient.
7.2. Development of new treatment methods
Studies on the development of new methods of treating hereditary diseases, such as gene therapy and editing genes, are ongoing.
7.3. Prevention of diseases
Genetic testing can be used to identify people with an increased risk of developing diseases. This can allow them to take preventive measures, such as a change in lifestyle and a more frequent examination.
7.4. Ethical questions
The development of genetics raises a number of ethical issues that need to be solved. It is necessary to ensure the confidentiality of genetic information and prevent discrimination based on genetic data.
7.5. Education and informing the population
It is important to inform the population about genetics and its effect on health. People should understand the risks and advantages of genetic testing and treatment. Knowing the basics of genetics allows people to make more reasonable decisions about their health.
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