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Genes and health: what is inherited
I. Fundamentals of human genetics: heredity in the smallest details
Human genetics is an extensive and complex area of science that studies heredity and variability of signs in humans. It is based on genes – DNA areas containing instructions for the synthesis of proteins that determine the structure and functions of cells, tissues and organs. Our genes are a kind of “drawing” obtained from our parents, which has a tremendous effect on our health, a predisposition to diseases, and even character characteristics.
A. DNA: Book of life written in four letters
Deoxyribonucleic acid (DNA) is a macromolecule that stores genetic information. Imagine a huge library where each book is a chromosome, and each page is a gene. DNA has the shape of a double spiral consisting of two threads twisted around each other. Each thread consists of nucleotides, “bricks” DNA. There are four types of nucleotides, characterized by the nitrogen base: adenine (a), thyme (t), cytosine (C) and guanine (G). The order of these grounds (a, t, c, g) determines the genetic code that is used for protein synthesis. The ATGC sequence determines which protein will be produced, and, therefore, what characteristics we will inherit.
B. Chromosomes: packaging of genetic information
DNA is not in a cage in a free state. It is packed in chromosomes – structures consisting of DNA and proteins (histones). In a person, in every somatic (non -head) cell contains 46 chromosomes organized in 23 pairs. We get one chromosome from each pair from the mother, the other from the father. The germ cells (sperm and eggs) contain 23 chromosomes. During fertilization, the germ cells are merged, and a full set of chromosomes is restored-46. Anomalies of the number of chromosomes (for example, trisomy according to the 21st chromosome with Down syndrome) lead to serious developmental disorders.
C. Genes: Units of hereditary information
The gene is a DNA section that encodes information about one protein. Each gene has a certain sequence of nucleotides, which determines the amino acid sequence of protein. Proteins perform many functions in the body: they are enzymes that catalyze chemical reactions, structural elements of cells and tissues, hormones that regulate various processes, and antibodies that protect from infections. Various forms of the same gene are called alleles. For example, the gene responsible for eye color can have alleles that determine blue, brown or green.
D. Genotype and phenotype: how genes appear in appearance and health
A genotype is a set of all genes that the body has. A phenotype is a set of all signs of the body that manifest as a result of the interaction of the genotype and the environment. For example, the genotype can be predisposed to high growth, but if a person eats poorly, his growth can be lower than expected. The phenotype is what we see (eye color, hair, height), as well as the functional characteristics of the body (the ability to digest lactose, a tendency to certain diseases). Not all genotype genotypes appear in the phenotype. Some genes can be “turned off” or “turned on” depending on various factors, such as age, nutrition, toxins and others. This is called the expression of genes.
II. Hereditary diseases: when genetics causes problems
Hereditary diseases are diseases caused by mutations in genes or abnormalities of the number of chromosomes. They are transmitted from parents to children and can appear at various ages. There are various types of inheritance of hereditary diseases:
A. Autosomas and dominant inheritance:
In this case, one copy of the mutant gene inherited from one of the parents is enough to manifest the disease. If one of the parents is sick, the probability of the birth of a sick child is 50%. Examples: neurofibromatosis, marfan syndrome, ahondroplasia (dwarf).
B. Autosomalmical recessive inheritance:
In this case, the disease manifests itself only when a person inherited two copies of the mutant gene, one from each parent. If both parents are carriers of the mutant gene (i.e. they have one copy of the mutant gene, but they themselves are healthy), the probability of the birth of a sick child is 25%. The probability of the birth of a ladder child is 50%, and the probability of the birth of a healthy child who is not a carrier is 25%. Examples: cystic fibrosis, phenylketonuria, sickle cell anemia.
C. X-linked dominant inheritance:
The disease that causes the disease is on the X chromosome. Women have two x chromosomes, therefore, one copy of the mutant gene is enough to manifest the disease. Men have one X-chromosome and one Y chromosome, so the presence of a mutant gene on the X chromosome always leads to the manifestation of the disease. If the mother is sick, the probability of the birth of a sick child (both a boy and a girl) is 50%. If his father is sick, all his daughters will be sick, and all his sons will be healthy. Examples: vitamin-D-resistant rickets, Retta syndrome (more often found in girls).
D. X-linked recessive inheritance:
The disease that causes the disease is on the X chromosome. In women, the disease manifests itself only when they inherited two copies of the mutant gene. In men, the disease always manifests itself when they inherited a mutant gene on their only x chromosome. Women are often carriers of the mutant gene, without showing the symptoms of the disease. If the mother is a carrier, the probability of the birth of a sick son is 50%. All daughters will be healthy, but 50% of them will be carriers. If his father is sick, all his daughters will be carriers, and all his sons will be healthy and will not be carriers. Examples: hemophilia, colortonism, muscle dystrophy of Duchenne.
E. Y-Continued inheritance:
The disease that causes the disease is on the Y chromosome. The disease is transmitted only from father to son. Women cannot inherit Y-linked diseases. Examples: some forms of infertility, an auricle hypertrichosis (ears of the auricle).
F. Mitochondrial inheritance:
Mitochondria is an organella of cells responsible for the production of energy. They have their own DNA. Mitochondrial diseases are transmitted only from mother to children. All children of the sick mother will be sick, regardless of gender. Fathers do not transmit mitochondrial diseases to their children. Examples: mitochondrial myopathy, lei syndrome.
G. Polygenic diseases:
Polygenic diseases are diseases caused by the interaction of several genes and environmental factors. They do not follow the classical laws of inheritance and are often found in families. The probability of developing a polygenic disease depends on many factors, including a genetic predisposition, lifestyle and environmental effects. Examples: type 2 diabetes, cardiovascular diseases, cancer, obesity, asthma, schizophrenia.
III. Disease predisposition: genes and risk of diseases
Not all diseases are purely hereditary. Many diseases develop as a result of the interaction of genes and environmental factors. Genes can increase or lower the risk of a certain disease. For example, a person can have a genetic predisposition to breast cancer, but if he leads a healthy lifestyle and regularly undergoes examinations, he can avoid the development of the disease or detect it at an early stage.
A. Cardiovascular diseases:
Heredity plays an important role in the development of cardiovascular diseases, such as coronary heart disease, myocardial infarction and stroke. Genes affect cholesterol, blood pressure, blood coagulation and other risk factors. If the family has cases of cardiovascular diseases at a young age, the risk of developing these diseases in descendants increases. However, a healthy lifestyle, including proper nutrition, physical activity and refusal of smoking, can significantly reduce the risk of developing cardiovascular diseases, even with a genetic predisposition.
B. Type 2 diabetes sugar:
Type 2 diabetes is a polygenic disease, the development of which is involved in several genes and environmental factors, such as obesity, insufficient physical activity and malnutrition. Genes affect sensitivity to insulin, insulin secretion and other factors associated with the regulation of blood glucose. If the family has type 2 diabetes mellitus, the risk of developing this disease in descendants increases. However, maintaining a healthy weight, regular physical activity and proper nutrition can significantly reduce the risk of developing type 2 diabetes, even in the presence of a genetic predisposition.
C. Cancer:
Cancer is a group of diseases characterized by uncontrolled growth and the spread of abnormal cells. Heredity plays a role in the development of some types of cancer, such as breast cancer, ovarian cancer, colon cancer and prostate cancer. Mutations in the BRCA1 and BRCA2 genes, for example, significantly increase the risk of developing breast cancer and ovarian cancer. However, most cases of cancer are not associated with hereditary mutations, but are caused by environmental factors, such as smoking, malnutrition, exposure to ultraviolet radiation and other carcinogens. Regular examinations and a healthy lifestyle can help in early detection and prevention of cancer.
D. Alzheimer’s disease:
Alzheimer’s disease is a neurodegenerative disease characterized by a progressive decrease in cognitive functions. Heredity plays a role in the development of an early form of Alzheimer’s disease, which manifests itself up to 65 years. Mutations in the App, Psen1 and Psen2 genes increase the risk of developing an early form of Alzheimer’s disease. However, most cases of Alzheimer’s disease are sporadic and develop at a later age. Alzheimer’s risk factors include age, genetic predisposition, cardiovascular disease, type 2 diabetes and head injuries. Maintaining a healthy lifestyle and mental activity can help reduce the risk of developing Alzheimer’s disease.
E. Autoimmune diseases:
Autoimmune diseases are a group of diseases in which the body’s immune system attacks its own cells and tissues. Heredity plays a role in the development of many autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis and psoriasis. Genes involved in the regulation of the immune system can increase or lower the risk of autoimmune diseases. Environmental factors, such as infections and stress, can also play a role in the development of autoimmune diseases.
IV. Genetic testing: to find out the future, knowing your past
Genetic testing is a DNA analysis for identifying mutations in genes or abnormalities of the number of chromosomes. Genetic testing can be used for various purposes:
A. Diagnostic testing:
Diagnostic testing is carried out to confirm or exclude the diagnosis of a hereditary disease in a person with symptoms of the disease. The results of diagnostic testing can help the doctor establish an accurate diagnosis and prescribe the appropriate treatment.
B. Predictive testing:
Predictive testing is carried out to determine the risk of developing a certain disease in the future. For example, prognostic testing can be used to assess the risk of breast cancer in women with the family history of this disease. The results of prognostic testing can help a person take measures to reduce the risk of developing the disease, such as regular examinations, a healthy lifestyle and preventive drugs.
C. Prenatal diagnostics:
Prenatal diagnosis is carried out during pregnancy to identify hereditary diseases or abnormalities of the number of chromosomes in the fetus. Prenatal diagnostic methods include amniocentesis, choriona biopsy and non -invasive prenatal testing (NIPT). The results of prenatal diagnostics can help parents decide on the continuation or termination of pregnancy.
D. Screening of newborns:
The screening of newborns is carried out to identify certain hereditary diseases in newborns. Early detection of these diseases allows you to begin treatment before the onset of symptoms, which can prevent serious complications. Examples of diseases detected during the screening of newborns: phenylketonuria, congenital hypothyroidism and cystic fibrosis.
E. Pharmacogenetics:
Pharmacogenetics is a study of the influence of genetic factors on the body’s reaction to medicines. Genetic tests can be used to determine how a person will respond to certain drugs. This information can help the doctor choose the most effective and safe medicine for a particular person.
V. Epigenetics: heredity that changes
Epigenetics is a study of changes in genes expression that are not associated with changes in the DNA sequence. Epigenetic changes can be caused by environmental factors, such as nutrition, stress and the effects of toxins. These changes can be transmitted from generation to generation. Epigenetics shows that our genes are not a static set of instructions, but a dynamic system that can change depending on our lifestyle and environment.
A. DNA methylation:
DNA methylation is the process of adding a methyl group to DNA. DNA methylation usually leads to suppression of genes expression. DNA methylation plays an important role in development, differentiation of cells and protection against viruses.
B. Modification Gistonov:
Histons are proteins around which DNA is wrapped. The modification of histones can change the structure of chromatin and influence the expression of genes. For example, acetylation of histones usually leads to activation of genes expression, and deecethylization to suppression of genes expression.
C. Micrornk:
Microrm is short RNA molecules that regulate the expression of genes, contacting MRNA and blocking its broadcast into protein. Microrm play an important role in development, differentiation of cells and immune response.
VI. Genetic consultation: Assistance in decision -making
Genetic consultation is the process of providing information and support to people who have hereditary diseases or are at risk for the development of these diseases. A genetic consultant is a specialist who is trained in the field of genetics and counseling. A genetic consultant can help:
- Assess the risk of developing a hereditary disease.
- Explain the options for genetic testing.
- Interpret the results of genetic tests.
- Develop a risk management plan.
- Provide support in decision -making.
Genetic consultation can be useful to people with a family history of hereditary diseases, pairs planning pregnancy, and people, concerned about the risk of developing certain diseases.
VII. Future of genetics and health: an individual approach to treatment
Genetics plays an increasingly important role in medicine. The development of genetic technologies allows you to develop new methods of diagnosis, prevention and treatment of diseases. In the future, medicine will become more individual, based on the genetic profile of each person.
A. Gene therapy:
Gene therapy is a method of treating diseases by introducing a gene of a patient into the cell, which is absent or operates incorrectly. Gene therapy is in the early stages of development, but has a great potential for the treatment of hereditary diseases and cancer.
B. Genoma editing:
Genoma editing is a method of accurately changing the DNA sequence. CRISPR-CAS9 technology, for example, allows you to easily and effectively edit cells in cells. The genome editing has great potential for the treatment of hereditary diseases, cancer and other diseases.
C. Personalized medicine:
Personalized medicine is an approach to treatment, which takes into account the genetic profile of each person. Genetic tests can be used to determine how a person will respond to certain drugs and to select the most effective and safe treatment.
VIII. Ethical questions of genetics:
The development of genetic technologies raises important ethical issues:
- Privacy of genetic information: who should have access to human genetic information?
- Discrimination based on genetic information: can employers or insurance companies discriminate people based on their genetic profile?
- Genoma editing: is it permissible to edit genes in embryos?
It is important to carefully discuss these ethical issues in order to ensure the responsible use of genetic technologies.
IX. Conclusion:
Genes play an important role in our health, predisposition to diseases and characteristics of character. Understanding genetics allows us to better understand ourselves and make more reasonable decisions about our health. The development of genetic technologies opens up new opportunities for the diagnosis, prevention and treatment of diseases. However, it is important to remember ethical issues related to genetics and strive to responsible use of genetic technologies.
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