Hereditary diseases: what do you need to know?

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Hereditary diseases: what do you need to know?

I. Fundamentals of genetics and heredity

  1. Chromosomes, genes and DNA:

    • Chromosomes: The human genome is organized in 23 pairs of chromosomes located in the core of each cell. One chromosome in each pair is inherited from the mother, and the other from the father. Chromosomes consist of DNA and proteins.

    • Genes: Genes are functional units of heredity, which are DNA areas encoding certain proteins or performing regulatory functions. Each gene has its own location on a chromosome called a locus.

    • DNA (deoxyribonucleic acid): DNA is a molecule that carries genetic information. It has the structure of a double spiral consisting of four nucleotides: adenina (a), tymin (t), cytosine (C) and guanine (G). The sequence of these nucleotides determines the genetic code.

  2. Inheritance and alleles:

    • Alleli: Most genes exist in several versions called alleles. Each person has two alleles of each gene, one from each parent.

    • Homozigi and heterozygosity: If a person has two identical alleles of a certain gene, he is considered a homozygous gene. If a person has two different alleles of a certain gene, he is considered a heterozygous for this gene.

    • Dominant and recessive inheritance: With dominant inheritance, one copy of the dominant allele is enough to manifest the sign. With recessive inheritance for the manifestation of a sign, it is necessary to have two copies of the recessive allele.

    • X-linked inheritance: Genes located on the sex X-chromosome are inherited according to a special mechanism. Women have two X-chromosomes, so they can be heterozygous in X-linked genes. In men, only one X-chromosome, so they always express X-scented genes, even if they have only one copy of the recessive allele.

  3. Mutations and their influence:

    • Mutations: Mutations are changes in the DNA sequence. They can occur spontaneously or under the influence of external factors, such as radiation or chemicals.

    • Types of mutations: Mutations can be different: the replacement of one nucleotide by another (point mutation), an insert or a deletion of nucleotides, the inversion of the DNA site, the translocation of the DNA site for another chromosome, etc.

    • The influence of mutations: The effect of mutations on the body can be different: some mutations do not lead to any noticeable changes (silent mutations), others can cause diseases or predisposition to them.

II. Types of hereditary diseases

  1. Monogenic diseases:

    • Definition: Monogenic diseases are due to mutation in one gene.

    • Types of inheritance: Monogenic diseases can be inherited by autosomal dominant, autosomal recessive or X-combined mechanism.

    • Examples:

      • 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. It affects the lungs, pancreas and other organs.

      • Phenylketonuria (FCU): An autosomal recessive disease caused by a mutation in the PAH gene, which encodes the enzyme phenylalain nyxilosis. Leads to the accumulation of phenylalanine in the blood and damage to the brain.

      • Huntington’s disease (Khorea Huntington): Autosomas and dominant disease caused by a mutation in the HTT gene, which encodes the Hunting protein. Leads to progressive degeneration of nerve cells in the brain.

      • Hemophilia: A X-linked recessive disease characterized by a impaired blood coagulation. There are several types of hemophilia caused by mutations in various genes encoding blood coagulation factors.

      • Duchenna myodystrophy: A X-linked recessive disease caused by a mutation in the DMD gene, which encodes the protein of dystrophin. Leads to progressive muscle weakness and degeneration.

  2. Chromosomal diseases:

    • Definition: Chromosomal diseases are due to a change in the number or structure of chromosomes.

    • Types of chromosomal anomalies: Anneuploidia (change in the number of chromosomes), deletions (loss of part of the chromosome), duplication (doubling of part of the chromosome), translocation (moving part of the chromosome to another chromosome), inversion (turning the chromosome area).

    • Examples:

      • Down Syndrome (Trisomy 21): The presence of three copies of the chromosome 21 instead of two. It is characterized by mental retardation, characteristic features of the face and other physical abnormalities.

      • Turner syndrome (monosomy x): The presence of only one X-chromosome in women (XO). It is characterized by low growth, ovarian underdevelopment and other physical abnormalities.

      • Klainfelter syndrome (XXY): The presence of two X-chromosomes and one Y-chromosome in men. It is characterized by infertility, high growth and other physical abnormalities.

      • Patau’s Syndrome (Trisomy 13): The presence of three copies of the chromosome 13 instead of two. It is characterized by severe physical abnormalities and mental retardation.

      • Edwards syndrome (Trisomy 18): The presence of three copies of the chromosome 18 instead of two. It is characterized by severe physical abnormalities and mental retardation.

  3. Multifactorial diseases:

    • Definition: Multifactor diseases are due to the interaction of genetic factors and environmental factors.

    • Features: The risk of developing multifactorial diseases depends on a combination of genetic options and the effects of environmental factors.

    • Examples:

      • Type 2 diabetes: The disease characterized by a violation of regulation of blood glucose levels. The risk of developing diabetes of the 2nd type depends on the genetic predisposition, overweight, insufficient physical activity and other factors.

      • Cardiovascular diseases (coronary heart disease, arterial hypertension): Diseases that affect the heart and blood vessels. The risk of developing cardiovascular diseases depends on the genetic predisposition, high level of cholesterol, smoking, high blood pressure and other factors.

      • Autoimmune diseases (rheumatoid arthritis, multiple sclerosis): Diseases in which the immune system attacks its own cells and tissues of the body. The risk of developing autoimmune diseases depends on the genetic predisposition, effects of infections and other factors.

      • Oncological diseases (breast cancer, colon cancer): Diseases characterized by uncontrolled cell growth. The risk of developing cancer depends on the genetic predisposition, exposure to carcinogens, smoking, malnutrition and other factors.

      • Alzheimer’s disease: Neurodegenerative disease, leading to a progressive loss of memory and cognitive functions. The risk of developing Alzheimer’s disease depends on the genetic predisposition, age and other factors.

  4. Mitochondrial diseases:

    • Definition: Mitochondrial diseases are due to mutations in the DNA of Mitochondria – Organelle, responsible for the production of energy in the cell.

    • Inheritance: Mitochondria inherited only from the mother.

    • Features: Mitochondrial diseases can affect various organs and systems, especially those that need a large amount of energy (brain, muscles, heart).

    • Examples:

      • MELAS (mitochondrial encephalomyopathy, lactacidosis and stroke -like episodes): The disease characterized by neurological disorders, muscle weakness and lactacidosis.

      • Merrf (myoclonic epilepsy with red torn fibers): The disease characterized by myoclonic convulsions, epilepsy and muscle weakness.

      • Leber’s hereditary optic neuropathy (LHON): The disease leading to a sudden loss of vision.

III. Diagnosis of hereditary diseases

  1. The prenatal diagnostics:

    • Definition: Diagnosis of hereditary diseases in the fetus during pregnancy.

    • Methods:

      • Screening of the first trimester: The risk assessment of chromosomal abnormalities based on the analysis of the blood of the mother and ultrasound examination of the fetus.

      • Amniocentez: The fence of amniotic fluid for analysis of the chromosomes of the fetus. It is usually carried out at 15-18 weeks of pregnancy.

      • Chorion Biopsy: The sample of the placenta tissue sample for the analysis of the chromosomes of the fetus. It is usually carried out at 10-12 weeks of pregnancy.

      • Cordocentesis: Blood sampling from the fetal umbilical cord for the analysis of chromosomes and genes. It is usually carried out after 18 weeks of pregnancy.

      • Non -invasive prenatal test (NIPT): Analysis of DNA of the fetus circulating in the blood of the mother. Allows you to identify chromosomal abnormalities and some genetic diseases.

    • Indications: The presence of hereditary diseases in the family, the age of the mother over 35, deviations based on the results of the screening of the first trimester.

  2. Post -ranked diagnostics:

    • Definition: Diagnosis of hereditary diseases in newborns and children.

    • Methods:

      • Neonatal screening: A mass examination of newborns for some hereditary diseases (phenylketonuria, congenital hypothyroidism, cystic fibrosis, etc.).

      • Clinical examination and history of the anamnesis: Assessment of symptoms and family history to detect hereditary diseases.

      • Genetic tests: DNA analysis for identifying mutations in genes associated with hereditary diseases.

      • Chromosomal analysis (karyotyping): Analysis of chromosomes to detect chromosomal abnormalities.

      • Biochemical tests: Analysis of the level of certain substances in the blood or urine to identify metabolic disorders associated with hereditary diseases.

      • Visualizing methods (X -ray, ultrasound, MRI): The use of visualizing methods to assess the state of organs and systems.

  3. Genetic counseling:

    • Definition: The process of providing information and support to people with the risk of developing or transmitting hereditary diseases.

    • Goals:

      • Assessment of the risk of developing or transmitting a hereditary disease.

      • Explanation of the characteristics of the inheritance of the disease.

      • Discussion of diagnostic and treatment options.

      • Support for making decisions related to family planning.

IV. Treatment and prevention of hereditary diseases

  1. Treatment:

    • Replacement therapy: Filling of the missing substances or enzymes (for example, replacement enzyme therapy for Gaucher’s disease).

    • Symptomatic treatment: Elimination or relief of the symptoms of the disease (for example, the use of broncholitics for cystic fibrosis).

    • Surgical treatment: Correction of anatomical defects (for example, surgical treatment of heart defects with Down syndrome).

    • Gene therapy: The introduction of genetic material into the cells of the body to correct a genetic defect.

    • Organ and tissue transplantation: Replacing the affected organ or tissue healthy (for example, bone marrow transplantation in some forms of immunodeficiency).

  2. Prevention:

    • Genetic counseling and family planning: Risk assessment and making decisions on family planning taking into account genetic predisposition.

    • Prenatal diagnosis and termination of pregnancy: Identification of hereditary diseases in the fetus and a decision on termination of pregnancy (for medical reasons).

    • Neonatal screening and early treatment: The identification of hereditary diseases in newborns and the timely start of treatment to prevent the development of complications.

    • Screening of carriage: Identification of carriers of recessive genetic diseases to assess the risk of the birth of a sick child.

    • Life change change: Compliance with diet, physical activity and rejection of bad habits to reduce the risk of developing multifactorial diseases.

V. Ethical and social aspects of hereditary diseases

  1. Confidentiality of genetic information: Ensuring the protection of genetic information from unauthorized access and use.

  2. Patient rights to genetic testing and counseling: Ensuring access to genetic testing and counseling for everyone who needs it.

  3. Discrimination based on genetic information: The ban on discrimination based on genetic information in the field of employment, insurance and other areas.

  4. Ethical issues of prenatal diagnosis and gene therapy: Discussion of ethical issues related to prenatal diagnosis, selection of embryos and genetic therapy.

  5. Social support for families with hereditary diseases: Providing social support for families raising children with hereditary diseases. This may include financial assistance, access to medical and rehabilitation services, psychological support and the ability to communicate with other families in a similar situation. It is important to create an inclusive environment where children with hereditary diseases can fully develop and participate in society.

VI. New technologies in the field of genetics and hereditary diseases

  1. New generation sequencing (NGS): A technology that allows you to quickly and effectively determine the DNA sequence. It is used to diagnose hereditary diseases, identify genetic predispositions and develop new treatment methods.

  2. CRISPR-CAS9: The genome editing system that allows you to accurately change the DNA sequence. Opens prospects for the treatment of hereditary diseases by correcting genetic defects.

  3. Personalized medicine: The approach to treatment based on the individual genetic characteristics of the patient. Allows you to choose the most effective treatment and reduce the risk of side effects.

  4. Bioinformatics: The field of science that is analyzing and interpreting large volumes of biological data, including genetic data. It helps to identify new genes associated with hereditary diseases and develop new methods of diagnosis and treatment.

  5. Artificial intelligence (AI): The use of AI in genetics and medicine allows you to analyze complex genetic data, predict the risk of diseases and develop new drugs. AI can also be used to automate the processes of diagnosis and monitoring of the condition of patients.

VII. Practical tips for families with the risk of hereditary diseases

  1. Family history collection: Carefully study the family history of health, paying attention to the presence of hereditary diseases in relatives.

  2. Application to the geneticist: Consult a geneticist to assess the risk of developing or transmitting a hereditary disease.

  3. Passage of genetic testing: Consider the possibility of passing genetic testing to identify carriage or the presence of genetic mutations.

  4. Pregnancy planning taking into account genetic risks: When planning pregnancy, discuss with a geneticist options for prenatal diagnosis and prevention of hereditary diseases.

  5. Informing other family members: Tell other family members about genetic risks so that they can make reasonable decisions about their health and family planning.

  6. Support and communication with other families: Join support groups or organizations for families with children with hereditary diseases. Communication with other families can help cope with emotional and practical difficulties.

  7. Studying information about a hereditary disease: Get reliable information about a hereditary disease, its symptoms, treatment and prevention from reliable sources.

  8. Compliance with the doctor’s recommendations: Follow the doctor’s recommendations for the treatment, prevention and monitoring of health status.

  9. Active participation in the treatment of a child: Actively participate in the process of treating the child, ask doctors and share your observations.

  10. Caring for yourself: Take time to care about yourself to maintain your physical and emotional health.

VIII. Frequently asked questions (FAQ) about hereditary diseases

  1. What is a hereditary disease?

    • A hereditary disease is a disease caused by a mutation in the gene or chromosome, which is transmitted from parents to children.

  2. How to find out if I have a risk of hereditary disease?

    • Risk can be evaluated on the basis of family history, genetic testing and consultation with a geneticist.

  3. What types of genetic tests exist?

    • There are various types of genetic tests, including neonatal screening, genetic testing of carriage, diagnostic genetic testing and prenatal genetic testing.

  4. What is genetic counseling?

    • Genetic counseling is the process of providing information and support to people who have the risk of developing or transmitting hereditary diseases.

  5. Is it possible to cure a hereditary disease?

    • Some hereditary diseases can be cured, while others can only control or relieve symptoms.

  6. What are the methods of preventing hereditary diseases?

    • Prevention methods include genetic counseling, prenatal diagnostics, neonatal screening and a change in lifestyle.

  7. Where can I get additional information about hereditary diseases?

    • Additional information can be obtained from a geneticist, in medical centers, specialized organizations and reliable Internet resources.

  8. What to do if my child was diagnosed with a hereditary disease?

    • Contact the geneticist and other specialists to obtain a consultation and develop a treatment plan. Join support groups for families with children with similar diseases.

  9. How do genetic diseases affect family planning?

    • Genetic diseases can affect family planning, as parents may want to evaluate the risk of transmitting the disease to their children and consider prenatal diagnostic options or alternative reproduction methods.

  10. What rights people with hereditary diseases have?

    • People with hereditary diseases are entitled to confidentiality of genetic information, access to genetic testing and counseling, as well as protection against discrimination based on genetic information.

IX. Glossary of the terms associated with hereditary diseases

  • Allele: Gene option.
  • AminoCentez: A prenatal procedure in which a small amount of amniotic fluid for genetic testing is removed from the uterus.
  • Autosome: Any chromosome that is not a sexual chromosome.
  • Autosomal dominant inheritance: The type of inheritance, in which one copy of the mutant gene is enough for the manifestation of the disease.
  • Autosomal recessive inheritance: The type of inheritance, in which two copies of the mutant gene are necessary for the manifestation of the disease.
  • Chorion Biopsy: A prenatal procedure in which a small amount of fabric for genetic testing is extracted from the placenta.
  • Genome: A complete set of genetic instructions of the body.
  • Gene: A unit of heredity, consisting of DNA and encoding a certain protein or performing a regulatory function.
  • Genetic counseling: The process of providing information and support to people with the risk of developing or transmitting hereditary diseases.
  • Genetic testing: DNA analysis for identifying mutations in genes or chromosomal abnormalities.
  • Genotype: The genetic constitution of the body.
  • Homozygot: Having two identical alleles of a certain gene.
  • Heterozygous: Having two different alleles of a certain gene.
  • DNA (deoxyribonucleic acid): A molecule bearing genetic information.
  • Karyotype: Chromosomal set of the body.
  • Cordocentesis: A prenatal procedure in which blood is extracted from the fetal umbilical cord for genetic testing.
  • Mitochondria: Organella in the cells responsible for the production of energy.
  • Mutation: Change in the sequence of DNA.
  • Neonatal screening: Mass examination of newborns for some hereditary diseases.
  • Phenotype: The observed characteristics of the body, which are the result of the interaction of the genotype and the environment.
  • Chromosome: A structure consisting of DNA and proteins, carrying genetic information.
  • X-linked inheritance: The type of inheritance in which the gene related to the disease is on the sex X-chromosome.

X. Links to useful resources and organizations

  1. National Institute of Health (NIH): https://www.nih.gov/
  2. Diseases control and prevention centers (CDC): https://www.cdc.gov/
  3. National Organization for rare diseases (Nord): https://rarediseases.org/
  4. Genetic and rare diseases (GARD) Information Center: https://rarediseases.info.nih.gov/
  5. European organization of rare diseases (Eurordis): https://www.eurordis.org/
  6. Local genetic centers and clinics: Search for a genetic center in your region to obtain consultation and testing.
  7. Forums and support groups for people with hereditary diseases: Online communities where you can communicate with other people faced with similar problems.
  8. Websites devoted to specific hereditary diseases: Search for information about a specific disease if it was diagnosed with you or your child.

This comprehensive article provides a wealth of information about genetic and hereditary diseases, covering their underlying mechanisms, different types, diagnostic methods, treatment options, ethical considerations, and emerging technologies. It also includes practical advice for families at risk and answers frequently asked questions. This article is designed to be informative, accessible, and empowering for readers seeking to understand and navigate the complexities of inherited diseases.

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