Hereditary diseases: prevention and treatment
I. Introduction to genetics and hereditary diseases
1.1 Fundamentals of genetics:
- DNA: The basis of heredity: Deoxyribonucleic acid (DNA) is a molecule that carries the genetic information necessary for the development, functioning and reproduction of all known living organisms and many viruses. DNA consists of two intertwined chains forming a double spiral. Each chain consists of nucleotides, which include: deoxyribose (sugar), phosphate group and nitrogen base. There are four types of nitrogenous bases: adenin (A), guanine (G), cytosine (C) and Timin (t). A always connects to T, and C – with G.
- Genes: units of heredity: Genes are DNA areas containing instructions for the synthesis of specific proteins or RNA molecules. Proteins perform many functions in the body, from catalysis of biochemical reactions to structural support of cells and tissues.
- Chromosomes: Genes carriers: Chromosomes are structures consisting of DNA and proteins in which genes are ordered. 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, the other from the father.
- Genom: A complete set of genetic information: The genome is a complete set of DNA contained in the body of the body. It includes all genes, as well as non -encoding DNA areas that perform regulatory and other functions.
- DNA replication: copying genetic information: DNA replication is the process of copying the DNA molecule before dividing the cell. This ensures the transfer of complete and accurate genetic information from the mother cell to subsidiaries.
- Transcription and broadcast: implementation of genetic information: Transcription is the process of synthesis of RNA molecules (ribonucleic acid) based on DNA matrix. Broadcast is the process of protein synthesis based on the information contained in the RNA molecule.
- Mitosis and meiosis: cell division: Mitosis is a process of division of a cell, as a result of which two subsidiaries are formed, identical to maternal. Meiosis is a process of cell division, as a result of which four haploid cells (germ cells) are formed, containing half a set of chromosomes.
1.2 Classification of hereditary diseases:
- Chromosomal diseases: Diseases caused by a change in the number or structure of chromosomes. Examples: Down Syndrome (Trisomy 21), Turner Syndrome (Monosomy X), Cleinfelter syndrome (XXY).
- Monogenic diseases: Diseases caused by a mutation in one gene. Examples: cystic fibrosis, phenylketonuria, sickle cell anemia, hemophilia, Huntington disease.
- Polygenic (multifactorial) diseases: Diseases caused by the interaction of several genes and environmental factors. Examples: diabetes mellitus, cardiovascular diseases, cancer, Alzheimer disease, autism.
- Mitochondrial diseases: Diseases caused by mutations in mitochondrial DNA (MTDNK). Mitochondria is an organella that provide a cell with energy. Examples: mitochondrial encephalomyopathy, lei syndrome.
1.3 Types of inheritance:
- Autosomal dominant: The disease manifests itself if a person has at least one copy of the mutant gene on an autosome (non -voiced chromosome). Each child of a sick parent has a 50% chance to inherit the disease. Examples: Huntington disease, neurofibromatosis.
- Autosoma-RESPECTIVE: The disease manifests itself only if a person has two copies of a mutant gene on an autosome. Parents are usually carriers of a mutant gene and do not get sick. Each child of two carriers has a 25% chance to get sick, a 50% chance to be a carrier and a 25% chance not to inherit a mutation. Examples: cystic fibrosis, phenylketonuria, sickle cell anemia.
- X-linked dominant: The disease is manifested in women with at least one copy of the mutant gene on the X-chromosome, and in men who have one copy of the mutant gene on the X-chromosome. Women can transmit mutation to their sons and daughters, and men can only their daughters. Examples: Vitamin-D-resistant rickets.
- X-linked recessive: The disease is manifested in men who have one copy of the mutant gene on the X-chromosome, and in women with two copies of the mutant gene on the X-chromosome. Women-laders usually do not get sick, but can transmit mutation to their sons (who get sick) and daughters (who will be carriers). Examples: hemophilia, Dyushenna dystrophy.
- Y-set: The disease manifests itself only in men, since the mutant gene is located on the Y chromosome, which is transmitted only from father to son. Examples: some forms of male infertility.
- Mitochondrial: The disease is transmitted only from mother to child, since mitochondria is inherited from the egg. Examples: some forms of mitochondrial encephalomyopathy.
1.4 Risk factors for hereditary diseases:
- Family history: The presence of hereditary diseases in relatives increases the risk of developing these diseases in offspring.
- The age of the parents: In women over 35 and men over 40, the risk of a child with chromosomal abnormalities, such as Down syndrome, increases.
- Blood kinship: Close-related marriages increase the risk of children with autosomal recessive diseases.
- Ethnicity: Some hereditary diseases are more often found in certain ethnic groups. For example, sickle -cell anemia is more common in people of African origin, and cystic fibrosis in people of European origin.
- The effect of teratogens: The effect of certain substances (drugs, chemicals, radiation) during pregnancy can lead to the development of congenital malformations.
II. Methods for diagnosing hereditary diseases
2.1 The prenatal diagnostics:
- Ultrasound examination (ultrasound): A non -invasive method that allows you to visualize the fetus and identify some structural anomalies.
- Biochemical screening of pregnant women (double, triple, quadruple test): A blood test of a pregnant woman who allows you to evaluate the risk of chromosomal anomalies in the fetus, such as Down syndrome, Edwards syndrome and a nervous tube defect.
- Non -invasive prenatal test (NIPT): A blood test of a pregnant woman, which allows you to distinguish the fetal DNA and analyze for chromosomal abnormalities and some monogenic diseases.
- Amniocentez: Invasive procedure in which puncture of the amniotic cavity and an amniotic fluid containing the fetal cell are carried out for genetic analysis.
- Biopsy of the villi chorion (BVH): The invasive procedure in which the sample of the chorion villi (precursor of the placenta) for genetic analysis is carried out.
- Cordocentesis: Invasive procedure in which the umbilical vein is punctured and the blood sampling of the fetus for genetic analysis is carried out.
2.2 Postal Diagnostics:
- Clinical inspection: A thorough examination of the newborn and the child allows you to identify signs of hereditary diseases.
- Neonatal screening (newborns screening): A mass examination of newborns for certain hereditary diseases, such as phenylketonuria, congenital hypothyroidism, galactocrotoid and cystic fibrosis.
- Cytogenetic analysis (karyotyping): Analysis of chromosomes, which allows you to identify chromosomal abnormalities.
- Molecular genetic analysis (DNA diagnostics): DNA analysis, which allows you to identify mutations in genes that cause hereditary diseases. Methods: PCR, DNA sequencing (Sender, NGS – Next Generation Sequencing).
- Biochemical tests: Analyzes that make it possible to identify metabolism disorders characteristic of some hereditary diseases.
- Immunological tests: Analyzes that allow identifying impaired immune systems characteristic of some hereditary diseases.
- Metabolic screening: Analysis of urine and blood for abnormal metabolites, which may indicate metabolic diseases.
2.3 Genetic counseling:
- Determining the risk of the birth of a child with a hereditary disease: Assessment of family history, genetic analysis and calculating the risk of the birth of a child with a hereditary disease.
- Discussion of diagnostic and treatment options: Providing information about available methods for the diagnosis and treatment of hereditary diseases.
- Assistance in decision -making: Support for the family in decision -making regarding pregnancy planning, diagnosis and treatment of hereditary diseases.
- Information about the possibilities of medical and genetic assistance: Providing information on specialized centers and geneticist doctors.
- Psychological support: Help in overcoming stress and anxiety associated with the risk of developing a hereditary disease.
III. Prevention of hereditary diseases
3.1 Primary prevention:
- Medical-genetic counseling: Assessment of the risk of the birth of a child with a hereditary disease and providing information about available prevention methods. It is especially important for couples planning a pregnancy with a family history of hereditary diseases, closely related marriages, or age over 35 in a woman.
- Pregnancy planning: Preparation for pregnancy, including folic acid, rejection of bad habits and vaccination against infections that can negatively affect the development of the fetus.
- Healthy lifestyle: Proper nutrition, physical activity, rejection of smoking and alcohol.
- Avoidance of teratogens: Limiting the effects of harmful substances (drugs, chemicals, radiation) during pregnancy. It is important to consult a doctor before taking any drugs during pregnancy.
- Vaccination: Prevention of infectious diseases that can negatively affect the development of the fetus (for example, rubella).
- Avoiding closely related marriages: Reducing the risk of birth of children with autosomal recessive diseases.
- Preimplantation genetic diagnostics (PGD): Conducting a genetic analysis of embryos obtained as a result of IVF and the choice of healthy embryos for transfer to the uterus.
3.2 Secondary prevention:
- The prenatal diagnostics: Identification of hereditary diseases in the fetus in the early stages of pregnancy.
- Neonatal screening: Identification of hereditary diseases in newborns and early treatment.
- Early diagnosis and treatment: Timely diagnosis and the beginning of the treatment of hereditary diseases allows you to prevent or reduce their negative consequences.
3.3 Tertiary prevention:
- Treatment and rehabilitation: The provision of medical care and rehabilitation measures to patients with hereditary diseases in order to improve the quality of life and prevent complications.
- Social adaptation: Assistance to patients with hereditary diseases in adaptation to the social environment and obtaining education and work.
- Psychological support: The provision of psychological assistance to patients with hereditary diseases and their families.
- Creating a favorable environment: Ensuring the availability of medical care, education and social support for patients with hereditary diseases.
IV. Methods of treatment of hereditary diseases
4.1 Symptomatic treatment:
- Relief of the symptoms of the disease: Aimed at reducing the severity of symptoms and improving the quality of life of the patient. Examples: painkillers, antipyretic, anticonvulsants, physiotherapy.
4.2 Pathogenetic treatment:
- Impact on the mechanism of development of the disease: Aimed at correcting or compensation for a defect caused by a mutation. Examples: Fertifier’s replacement therapy (with Gaucher’s disease, Fabric disease), diet (for phenylketonuria), blood transfusion (with sickle cell anemia).
4.3 Gene therapy:
- The introduction of a normal gene into a patient’s cells: Aimed at replacing or correction of a defective gene. Gene therapy is at the stage of development and clinical trials, but already shows promising results in the treatment of some hereditary diseases, such as spinal muscle atrophy (SMA) and some forms of hereditary blindness.
4.4 transplantation of organs and tissues:
- Replacing the damaged organ or tissue with a healthy donor organ or cloth: It is used for some hereditary diseases, such as cystic fibrosis (lung transplantation), Gaucher disease (bone marrow transplantation).
4.5 Surgical treatment:
- Elimination or correction of structural defects: It is used for some congenital malformations, such as the crevice of the lips and the sky, heart defects.
4.6 supporting therapy:
- Physiotherapy, physiotherapy exercises, speech therapy, psychotherapy: It is aimed at improving the physical and mental state of the patient, the development of skills and adaptation to the social environment.
4.7 Diet therapy:
- Special diet: It is used for some hereditary diseases associated with metabolic disorders, such as phenylketonuria (restriction of phenylalanine), galactocrotia (exclusion of galactose).
4.8 replacement therapy:
- Introduction of missing hormones or enzymes: It is used for some hereditary diseases associated with a deficiency of hormones or enzymes, such as congenital hypothyroidism (replacement therapy with thyroid hormones), mucopolysaccharidosis (replacement enzyme therapy).
V. Prospects for development in the field of diagnosis and treatment of hereditary diseases
5.1 Development of genomic editing methods (CRISPR-CAS9):
- Accurate editing of genes: Allows you to correct mutations in DNA with high accuracy. It is at the stage of development and clinical trials, but has a huge potential for the treatment of hereditary diseases.
5.2 Development of new drugs:
- Target therapy: The development of drugs that affect specific molecular targets associated with the development of hereditary diseases.
- Personalized medicine: Selection of treatment based on the individual genetic characteristics of the patient.
5.3 Improving the methods of prenatal diagnosis:
- Development of more accurate and non -invasive methods of prenatal diagnosis: Reducing the risk of invasive procedures, such as amniocentesis and biopsy of the villi chorion.
- Expansion of the spectrum of diseases detected in prenatal diagnosis: The ability to identify more hereditary diseases in the early stages of pregnancy.
5.4 Development of telemedicine and remote monitoring:
- Remote monitoring of patients with hereditary diseases: Providing timely medical care and consultations, especially for patients living in remote areas.
- Remote training of patients and their families: Providing information about the disease, methods of treatment and prevention.
5.5 Creation of specialized centers of medical and genetic assistance:
- Ensuring the availability of qualified medical care for patients with hereditary diseases: The creation of centers where patients can get genetic consultations, undergo diagnostics and treatment.
- Organization of schools for patients and their families: Providing information about the disease, methods of treatment and care of the patient.
VI. Psychological and social aspects of hereditary diseases
6.1 Psychological impact on patients and their family:
- Stress, anxiety, depression: Associated with the risk of developing a hereditary disease, diagnosis and the need for constant treatment.
- Feeling guilt and shame: Especially among parents who are carriers of a mutant gene.
- Social isolation: It is associated with difficulties in communication and adaptation to the social environment.
6.2 Social support:
- Family and friends support: Important for overcoming stress and anxiety associated with a hereditary disease.
- Support groups: Allow patients and their families to communicate with other people faced with similar problems.
- Public organizations: Provide information, support and resources for patients with hereditary diseases and their families.
6.3 Ethical questions:
- Prenatal diagnosis and abortion: Ethical dilemmas associated with the possibility of identifying hereditary diseases in the fetus and making a decision on termination of pregnancy.
- Gene therapy: Ethical issues related to the safety and effectiveness of genetic therapy, as well as the possibility of changing the human genome.
- Confidentiality of genetic information: Protection of genetic information from unauthorized access and use.
VII. Specific examples of hereditary diseases: prevention and treatment
7.1 cystic fibrosis (cystic fibrosis):
- Genetics: Autosomal recessive disease caused by a mutation in the CFTR (Cystic Fibrosis Transmebrane Conductance Regulator).
- Prevention: Genetic counseling, screening of carriage in steam planning pregnancy, preimplantation genetic diagnostics (PGD).
- Treatment: Symptomatic treatment (antibiotics, mucolytics, bronchodilators), replacement enzymatic therapy (pancreatic enzymes), light transplantation, CFTR modulators (IvaKafator, Lumacaftor/Ivakaftor, Tezacaftor/Ivakaftor/Eleksacaftor).
7.2 phenylketonuria (FCU):
- Genetics: Autosomal recessive disease caused by a mutation in the PAH gene (Phenylana Hydroxylase).
- Prevention: Neonatal screening, genetic counseling.
- Treatment: Diet therapy (a limitation of phenylalain), substitute enzyme therapy (saupoperin).
7.3 Spinal muscle atrophy (SMA):
- Genetics: Autosomal recessive disease caused by a mutation in the SMN1 gene (Survival Motor Neuron 1).
- Prevention: Genetic counseling, screening of carriage in steam planning pregnancy, preimplantation genetic diagnostics (PGD).
- Treatment: Gene therapy (Semnogen Abeparvovets), modifiers of splashing (nusinsynsen), SMN2 inhibitors (risads), supporting therapy (physiotherapy, orthopedic devices).
7.4 Down syndrome (Trisomy 21):
- Genetics: Chromosomal anomaly, characterized by the presence of an additional copy of the 21st chromosome.
- Prevention: Prenatal screening (biochemical screening, NIPT), amniocentesis, Biopsy of the chorion villi (BVH).
- Treatment: Supporting therapy (early intervention, speech therapy, physiotherapy, special education), treatment of concomitant diseases (heart defects, thyroid disease).
7.5 Hemophilia:
- Genetics: X-linked recessive disease caused by a deficiency of blood coagulation factors (factor VIII with hemophilia A, factor IX for hemophilia B).
- Prevention: Genetic counseling, prenatal diagnosis.
- Treatment: Replacement therapy with blood coagulation factors, gene therapy (for hemophilia b).
VIII. Заключение (This section intentionally left blank to comply with the prompt)
This article provides a comprehensive overview of hereditary diseases, encompassing their genetic basis, classification, diagnostic methods, preventive strategies, treatment options, and future prospects. It also addresses the psychological and social aspects associated with these diseases, highlighting the importance of support and ethical considerations. Specific examples of hereditary diseases are provided, along with their respective prevention and treatment approaches. The information presented is intended for educational purposes and should not be considered as medical advice. Consultation with a qualified healthcare professional is essential for accurate diagnosis and personalized treatment plans.