Genetics and health: Inheritance influence

Genetics and health: Inheritance influence

I. Fundamentals of human genetics and heredity

1. Genes: the main units of heredity. Genes are fundamental units of heredity contained in DNA (deoxyribonucleic acid). They encode the information necessary for the synthesis of proteins, which, in turn, perform a wide range of functions in the body. Each gene occupies a certain position (locus) on the chromosome. DNA consists of two complementary circuits twisted into a double spiral. Each chain consists of nucleotides consisting of sugar (deoxybosis), phosphate group and nitrogen base (adenine, tymin, guanine or cytosine). Adenin (a) is always connected to Timin (t), and guanine (G) is always combined with cytosin (C). The sequence of these grounds determines the genetic information.

2. Chromosomes: carriers of genetic information. A person has 46 chromosomes organized at 23 pairs. 22 pairs are called autosomes, and one pair – with sexual chromosomes (XX in women and XY in men). Each pair consists of one chromosome inherited from the mother, and one chromosome inherited from the father. Chromosomes are long DNA threads, tightly packed with proteins called histones. This organization allows you to effectively store and transmit genetic information during cellular division. Each chromosome contains many genes.

3. Genom: a complete set of genetic instructions. 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 play an important role in the regulation of genes expression. The decoding of the human genome (the “human genome” project) made it possible to obtain a huge amount of information about the genetic basis of health and disease. The sequencing of the genome has become more affordable and fast, which opens up opportunities for personalized medicine.

4. Genotype and phenotype: the interaction of genes and the environment. The genotype describes the genetic constitution of the body, that is, the totality of all its genes. The phenotype is the observed characteristics of the body, including physical, physiological and behavioral characteristics. The phenotype is the result of the interaction between the genotype and the environment. For example, a person can have a genetic predisposition to high growth (genotype), but its actual growth (phenotype) will depend on the nutrition and other environmental factors.

5. Allele: Genes options. Alleles are various forms of the same gene. For example, a gene that determines the color of the eyes can have alleles for brown eyes, blue eyes, etc. In diploid organisms, such as a person, each gene is represented by two alleles, one from each parent. If two alleles are the same, the body is called homozygous in this gene. If two alleles are different, the body is called heterozygous in this gene.

6. Mendel’s laws: basic principles of heredity. The laws of Mendel, formulated by Gregor Mendel based on experiments with peas, are the basis of modern genetics. The first law (the law of the uniformity of the first generation hybrids) claims that when crossing two homozygous organisms that differ according to one feature, all the first generation hybrids will be uniform on this basis. The second law (the law of splitting) claims that when crossing the first generation hybrids in the second generation, the signs are split in a certain ratio (usually 3: 1 for a dominant and recessive sign). The third law (the law of independent inheritance of signs) claims that genes located on different chromosomes are inherited independently of each other. It is important to note that not all signs are inherited in accordance with the simple Mendelev rules. Many signs are determined by several genes (polygenic inheritance) or the interaction of genes (epistasis).

7. Mutations: changes in genetic material. Mutations are changes in the DNA sequence. They can occur spontaneously or under the influence of mutagenes (for example, radiation, chemicals). Mutations can be both harmful and useful, or neutral. Harmful mutations can lead to the development of genetic diseases. Useful mutations can increase the body’s adaptability to the environment. Neutral mutations do not have a significant impact on the phenotype. Mutations can be accurate (a change in one nucleotide) or chromosomal (change in the structure or number of chromosomes).

II. Hereditary diseases: classification and development mechanisms

1. Monogenic diseases: diseases caused by mutations in one gene. Monogenic diseases are due to mutations in one gene. They are inherited in accordance with the Mendelev laws. Examples of monogenic diseases include:

   • Autosomal dominant diseases: The disease manifests itself if a person has inherited at least one copy of the mutant gene. Examples: Huntington disease, neurofibromatosis.
   • Autosomal recessive diseases: The disease is manifested only if a person inherited two copies of the mutant gene (one from each parent). Examples: cystic fibrosis, phenylketonuria, sickle cell anemia.
   • X-linked dominant diseases: The disease manifests itself in women if they inherited at least one copy of the mutant gene on the X chromosome. In men, the disease manifests itself if they inherited the mutant gene on their only x chromosome.
   • X-linked recessive diseases: The disease manifests itself in men if they inherited the mutant gene on their only X chromosome. In women, the disease manifests itself only if they inherited two copies of the mutant gene (one from each parent). Examples: hemophilia, colortonism.
   • Y-linked diseases: The disease manifests itself only in men, since the Y chromosome is present only in men.

2. Chromosomal diseases: diseases caused by changes in the number or structure of chromosomes. Chromosomal diseases occur due to anomalies in the amount or structure of chromosomes. Examples:

   • Down Syndrome (Trisomy 21): The presence of three copies of the 21st chromosome. It is characterized by mental retardation, characteristic features of the face, heart defects and other health problems.
   • Turner’s syndrome (monosome X): The presence of only one x chromosome in women. It is characterized by low growth, infertility and other abnormalities.
   • Klainfelter syndrome (XXY): The presence of two X chromosomes and one Y Cromosomes in men. It is characterized by infertility, high growth and other abnormalities.
   • Patau’s Syndrome (Trisomy 13): The presence of three copies of the 13th chromosome. It is characterized by severe malformations, mental retardation and short life span.
   • Edwards syndrome (Trisomy 18): The presence of three copies of the 18th chromosome. It is characterized by severe malformations, mental retardation and short life span.
   • Deletions: Loss of part of the chromosome.
   • Duplications: Doubling part of the chromosome.
   • Translocations: The transfer of part of the chromosome to another chromosome.
   • Inversions: The coup of the chromosome site is 180 degrees.

3. Multifactorial diseases: diseases caused by the interaction of genetic and environmental factors. Multifactor diseases are due to the interaction of many genes and environmental factors. They are not inherited in accordance with the simple Mendelev rules. Examples:

   • Cardiovascular diseases: Ichemic heart disease, hypertension, stroke.
   • Diabetes: Type 1 diabetes, type 2 diabetes.
   • Cancer: Many types of cancer have a genetic predisposition.
   • Autoimmune diseases: Rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis.
   • Mental illness: Schizophrenia, bipolar disorder, depression.
   • Congenital malformations: Cleat lips and heaven, heart defects.

4. Mitochondrial diseases: diseases caused by mutations in mitochondrial DNA. Mitochondria is organelles present in cells that are responsible for energy production. They contain their own DNA (MTDNK), which is transmitted along the maternal line. Mutations in MTDNK can lead to the development of mitochondrial diseases that affect various organs and systems, especially those that require a large amount of energy, such as brain, muscles and heart.

5. Epigenetic changes: changes in genes expression not associated with a change in the sequence of DNA. Epigenetics studies changes in genes expression that are not associated with a change in the sequence of DNA. These changes can be caused by various environmental factors, such as nutrition, stress and the effect of toxic substances. Epigenetic changes can be transmitted from generation to generation and affect the risk of developing diseases. Examples of epigenetic mechanisms include:

   • DNA methylation: Adding a methyl group to cytosin in DNA. DNA methylation usually suppresses genes.
   • Modification of histones: Changes in the structure of histones, proteins around which DNA is wrapped. Histonian modifications can either stimulate or suppress the expression of genes.
   • Microrm (Markn): Small RNA molecules that regulate the expression of genes, contacting MRNA (matrix RNA) and blocking its broadcast.

III. Methods for diagnosing hereditary diseases

1. Prenatal diagnosis: Diagnosis of diseases in the fetus before birth. Prenatal diagnosis allows you to identify hereditary diseases in the fetus before birth. This enables parents to make an informed decision on the further fate of pregnancy. Prenatal diagnostic methods include:

   • Ultrasound examination (ultrasound): Using sound waves to create an image of the fetus. Ultrasound allows you to identify some structural anomalies.
   • Amniocentez: The fence of a small amount of amniotic fluid (fluid surrounding the fetus) for the analysis of fetal cells. Amniocentesis is usually performed at 15-18 weeks of pregnancy.
   • Horion Biopsy (BHV): The fence of a small chorion tissue (placenta) for the analysis of fetal cells. BHV is usually held at 10-12 weeks of pregnancy.
   • Cordocentesis: The fence of a small amount of blood from the umbilical vein for the analysis of fetal cells. Cordocentesis is usually performed after 18 weeks of pregnancy.
   • Non -invasive prenatal screening (NIPS): Analysis of DNA of the fetus contained in the blood of the mother. NIPS allows you to identify the most common chromosomal abnormalities, such as Down syndrome.

2. Postnatal diagnosis: Diagnosis of diseases after birth. Postnatal diagnosis is carried out after the birth of a child. Postnatal diagnostic methods include:

   • Clinical inspection: A thorough examination of the child by a doctor to identify signs of a hereditary disease.
   • Laboratory tests: A test of blood, urine and other biological fluids to detect biochemical markers of hereditary diseases.
   • Cytogenetic analysis (karyotyping): Analysis of chromosomes to detect chromosomal abnormalities.
   • Molecular genetic tests: DNA analysis to identify mutations in genes that cause hereditary diseases. Methods of molecular genetic diagnostics include:
     • PCR (polymerase chain reaction): An increase in the number of a specific DNA section to facilitate its analysis.
     • DNA sequencing: Determination of the sequence of nucleotides in DNA.
     • DNA microchips: Analysis of genes expression.
     • Eczu sequencing: Sequencing of all protein-coding genes (exom) in the genome.
     • Sequencing of the entire genome: Sequencing of the entire genome, including coding and non -dodging areas of DNA.

3. Genetic counseling: assessment of the risk of hereditary diseases and providing information about possible options. Genetic counseling is a process during which a geneticist or other specialist in the field of genetics evaluates the risk of developing a hereditary disease in a person or his offspring and provides information about possible actions. Genetic counseling can be useful for:

   • Families in which there are members with a hereditary disease.
   • Steam planning pregnancy.
   • People who want to find out their genetic risk of developing certain diseases.
   • People who have identified anomalous results of screening tests.

IV. Methods of treatment of hereditary diseases

1. Symptomatic treatment: elimination or relief of the symptoms of the disease. Symptomatic treatment is aimed at eliminating or alleviating the symptoms of the disease, but does not affect the main cause of the disease. Examples:

   • Anesthetic drugs: To relieve pain.
   • Anticonvulsants: To control seizures.
   • Physiotherapy: To improve motor functions.
   • Special diet: To control the level of certain substances in the blood (for example, phenylalanine with phenylketonuria).

2. Replacement therapy: replacement of absent or defective protein. Replacing therapy is aimed at replacing the absent or defective protein that causes the disease. Examples:

   • Insulin injections: With type 1 diabetes.
   • Blood transfusion: With sickle cell anemia.
   • Enzyme replacement therapy: With some lysosomal accumulation diseases.

3. Transplantation: replacing the affected organ or tissue healthy. Transplantation is a replacement of the affected organ or tissue healthy. Examples:

   • Bone marrow transplantation: In some genetic diseases of the blood.
   • Transplantation Baked: In some genetic liver diseases.
   • Lung transplantation: For cystic fibrous.

4. Gene therapy: the introduction of genetic material into the patient’s cells to treat the disease. Gene therapy is an experimental treatment method, which includes the introduction of genetic material into the patient’s cells to treat the disease. Gene therapy can be directed at:

   • Replacing a defective gene with a healthy genome.
   • Inactivation of a defective gene.
   • The introduction of a gene that encodes a protein that can fight the disease.

5. Genoma editing: using technologies such as CRISPR-CAS9 to make accurate changes in DNA. Genoma editing is a new technology that allows you to make accurate changes to DNA. CRISPR-CAS9 is the most common genome editing system. It allows scientists to “cut out” a certain area of ​​DNA and replace it with others. The genome editing has a huge potential for the treatment of hereditary diseases, but also raises ethical issues.

V. Genetics and prevention of diseases

1. Genetic screening: identification of people with an increased risk of developing certain diseases. Genetic screening is a process of identifying people with an increased risk of developing certain diseases based on their genetic profile. Genetic screening can be useful for:

   • Identification of people with a predisposition to cancer development.
   • Identification of people with a predisposition to the development of cardiovascular diseases.
   • Identification of people with a predisposition to the development of diabetes.
   • Assessment of the risk of transmission of hereditary disease to offspring.

2. Personalized medicine: the use of genetic information to develop individual treatment plans and prevention of diseases. Personalized medicine is an approach to the treatment and prevention of diseases, which takes into account the individual genetic characteristics of the patient. Personalized medicine can allow:

   • Choose the most effective medicines for a particular patient.
   • Avoid drugs that can cause side effects in a particular patient.
   • To develop individual plans for the prevention of diseases.
   • Optimize the dosage of drugs.

3. Healthy lifestyle: reducing the risk of developing multifactorial diseases. A healthy lifestyle plays an important role in reducing the risk of developing multifactorial diseases, such as cardiovascular diseases, diabetes and cancer. A healthy lifestyle includes:

   • Balanced diet.
   • Regular physical exercises.
   • Refusal of smoking.
   • Restriction of alcohol consumption.
   • Maintaining a healthy weight.
   • Stress management.

4. Preventive measures: reducing the effects of environmental factors that can contribute to the development of diseases. Preventive measures aimed at reducing the impact of environmental factors can also help reduce the risk of developing certain diseases. Examples:

   • Vaccination: Protects from infectious diseases that can cause complications leading to the development of other diseases.
   • Avoiding the effects of toxic substances: Reduces the risk of cancer and other diseases.
   • Use of sunscreen: Reduces the risk of skin cancer.
   • Regular medical examinations: Allow you to identify diseases in the early stages when they are more treated.

VI. Ethical issues related to genetics

1. Confidentiality of genetic information: Protection of genetic information from unauthorized access and use. Genetic information is confidential and must be protected from unauthorized access and use. There are fears that genetic information can be used to discriminate in the field of employment, insurance and other areas.

2. Genetic testing of children: Balance between the right of parents to receive information about the health of the child and the right of the child for an open future. Genetic testing of children raises ethical issues related to the balance between the right of parents to receive information about the health of the child and the right of the child to an open future. Some experts believe that genetic testing of children should only be carried out if it is necessary to make decisions on the treatment or prevention of diseases.

3. Editing the human genome: potential advantages and risks of changing the human genome, especially the germline. Editing the human genome, especially the embryo line (spermatozoa and eggs), raises serious ethical issues. Changes in the embryo line will be transmitted to future generations, and the consequences of these changes can be unpredictable. There are fears that editing the genome can be used to create “designer children” with specified characteristics.

4. The availability of genetic technologies: ensuring equal access to genetic technologies for all, regardless of their socio-economic status. The availability of genetic technologies is an important issue. It is necessary to ensure equal access to genetic technologies for all, regardless of their socio-economic status. Otherwise, genetic technologies can aggravate the existing inequality in society.

VII. Future of genetics and healthcare

1. The development of new methods of diagnosis and treatment of hereditary diseases. In the future, the development of new and more effective methods for the diagnosis and treatment of hereditary diseases, including gene therapy, genome editing and personalized medicine, is expected.

2. A deeper understanding of the genetic basis of complex diseases. Studies in the field of genetics will help to obtain a deeper understanding of the genetic basis of complex diseases, such as cardiovascular diseases, diabetes and cancer.

3. Improving the prevention and early diagnosis of diseases. Genetic screening and personalized medicine will improve the prevention and early diagnosis of diseases, which will lead to an improvement in public health.

4. Solving ethical issues related to genetics. It is necessary to develop clear ethical principles and rules governing the use of genetic technologies to ensure their safe and fair use.

5. Integration of genetics into the healthcare system. Genetics will more and more integrate into the healthcare system, which will lead to a more personalized and effective approach to the treatment and prevention of diseases. This will require the training of doctors and other medical workers in the field of genetics and genomics. It will also be necessary to develop new financing and insurance models that will take into account genetic information. Expanding access to genetic testing and counseling will play an important role in improving the health of the population.