Genetic Disorders Explained

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Questions and Answers

Which of the following scenarios can lead to a genetic disease?

  • Having one or more abnormal genes.
  • Having missing genes.
  • Having extra genes.
  • All of the above. (correct)

Genes, as the building blocks of heredity, are created during an organism's development and are not passed down from parents.

False (B)

What are the four nucleic acids that combine in different ways to form DNA?

adenine, thymine, cytosine, guanine

In human cells, there are typically ______ pairs of chromosomes.

<p>23</p> Signup and view all the answers

Match the following terms with their correct association in genetics:

<p>Genes = Building blocks of heredity DNA = Molecule containing genes Proteins = Carry out cellular work Chromosomes = Structures housing DNA</p> Signup and view all the answers

Which of the following statements accurately describes the role of proteins in cells?

<p>Transporting molecules and building structures. (D)</p> Signup and view all the answers

Mutations in genes always lead to genetic disorders.

<p>False (B)</p> Signup and view all the answers

What term describes a change in a gene or genes that can lead to genetic disorders?

<p>mutation</p> Signup and view all the answers

The term for inheriting a gene mutation from one or both parents is ______.

<p>inherit</p> Signup and view all the answers

Match each type of cell with its role in transmitting hereditary mutations:

<p>Egg cells = Transmit hereditary mutations from the mother Sperm cells = Transmit hereditary mutations from the father Somatic cells = Do not transmit mutations to the next generation</p> Signup and view all the answers

If an individual is a carrier for a genetic disorder, which statement is most accurate?

<p>They will not experience disease symptoms but can pass the trait to their children. (B)</p> Signup and view all the answers

Genetic conditions are always inherited from parents and cannot occur spontaneously.

<p>False (B)</p> Signup and view all the answers

What term describes mutations that occur during a person's lifetime and are present only in certain cells?

<p>Acquired mutations</p> Signup and view all the answers

A hereditary mutation, also known as a ______ mutation, is present in virtually every cell in the body because it is inherited from a parent.

<p>germ line</p> Signup and view all the answers

Connect each type of genetic disorder with its primary characteristic:

<p>Single-gene disorders = Mutation affects one gene Chromosomal disorders = Chromosomes are missing or changed Complex disorders = Mutations in two or more genes</p> Signup and view all the answers

Which genetic disorder is caused by mutations in multiple genes, influenced by lifestyle and environmental factors?

<p>Colon cancer. (D)</p> Signup and view all the answers

Genetic tests are only useful for diagnosing diseases in unborn babies.

<p>False (B)</p> Signup and view all the answers

Name three methods used to diagnose genetic disorders.

<p>Physical Examination, Personal Medical History, Family Medical History</p> Signup and view all the answers

Prenatal diagnosis can detect fetal abnormalities through ultrasound or invasive procedures such as ______, which involves inserting probes into the uterus.

<p>amniocentesis</p> Signup and view all the answers

Match each diagnostic method with its focus in identifying genetic disorders:

<p>Physical examination = Observational characteristics such as facial features Personal medical history = Past health issues Family medical history = Health of family members Laboratory tests = Molecular, chromosomal, and biochemical indicators</p> Signup and view all the answers

Which of the following is an autosomal dominant disorder?

<p>Huntington's disease (B)</p> Signup and view all the answers

Symptoms of Huntington's Disease always begin in childhood.

<p>False (B)</p> Signup and view all the answers

What are the symptoms of Huntington's disease. Name at least 3?

<p>Uncontrolled movement (chorea), difficulty swallowing, behavioral changes</p> Signup and view all the answers

Down Syndrome, which typically appears in older expectant mothers, appears when an extra copy of genes occurs on chromosome ______.

<p>21</p> Signup and view all the answers

Connect each type of Down syndrome with its cause:

<p>Trisomy 21 = Abnormal cell division during sperm or egg development Mosaic Down syndrome = Abnormal cell division after fertilization Translocation Down syndrome = Part of chromosome 21 attaches to another chromosome</p> Signup and view all the answers

Which of the following statements accurately describes trisomy 21?

<p>The child has three copies of chromosome 21. (D)</p> Signup and view all the answers

Duchenne Muscular Dystrophy typically shows itself after the age of 6.

<p>False (B)</p> Signup and view all the answers

What are the the symptoms for Duchenne Muscular Dystrophy?

<p>fatigue, weakness of the muscles, Heart and respiratory difficulties</p> Signup and view all the answers

Duchenne Muscular Dystrophy often causes fatigue and muscle weakness that progresses, leading individuals to be wheelchair-bound by age ______.

<p>12</p> Signup and view all the answers

Match each disorder with its typical onset or characteristic:

<p>Huntington's Disease = Onset in adulthood Down Syndrome = Extra copy of chromosome 21 Duchenne Muscular Dystrophy = Muscle weakness starting in early childhood</p> Signup and view all the answers

Treatments in genetic conditions focus primarily on:

<p>Alleviating symptoms to improve the patient's quality of life. (C)</p> Signup and view all the answers

Since a healthy gene is introduced to a patient, gene therapy is considered a cure to genetic disorders.

<p>False (B)</p> Signup and view all the answers

Why is delivery of genes considered a major problem in gene therapy?

<p>Major obstacle in delivering the genes to the appropriate cell, tissue, and organ affected by the disorder</p> Signup and view all the answers

Not all genetic disorders directly result in death however there are no known ______ for genetic disorders

<p>cures</p> Signup and view all the answers

Match each genetic condition with its typical effect on the individual.

<p>Down syndrome = Affects stages of development Muscular Dystrophy = Leads to purely physical symptoms Huntington's Disease = Shows no signs until adulthood</p> Signup and view all the answers

If a geneticist suspects a new patient has a genetic disorder, which of the following is the first course of action they should most likely take?

<p>Thorough physical examination (D)</p> Signup and view all the answers

If somebody has a genetic mutation, they will express the properties of that genetic mutation during their entire lifetime.

<p>False (B)</p> Signup and view all the answers

What are genetic tests?

<p>tests on blood and other tissue to find genetic disorders</p> Signup and view all the answers

Genetic conditions are usually ______, meaning that they are passed down from parents to their children.

<p>inherited</p> Signup and view all the answers

Connect each with the term associated

<p>ADA Immune Deficiency = First hereditary condition treated by gene therapy Werner Syndrome = Premature aging Azoosperima = Absence of sperm in semen</p> Signup and view all the answers

In the context of genetic disorders, what is the primary role of proteins within cells?

<p>To execute various cellular functions which include transporting molecules, constructing structures, and neutralizing toxins (D)</p> Signup and view all the answers

A genetic mutation in a parent's somatic cells will always be inherited by their offspring.

<p>False (B)</p> Signup and view all the answers

What are the implications for offspring if a parent has Huntington's Disease, given that it is an autosomal dominant disorder?

<p>50 percent chance of inheriting the disease</p> Signup and view all the answers

The genetic condition known as Trisomy 21, commonly referred to as _______, is caused by an additional copy of chromosome 21.

<p>Down syndrome</p> Signup and view all the answers

Match the prenatal diagnostic procedure with its primary diagnostic method:

<p>Amniocentesis = Detects the presence of characteristic substances via invasive procedures Chorionic villus sampling (CVS) = Involves removing a small sample of cells from the placenta to test for chromosomal or genetic disorders Ultrasound = Detects characteristic abnormalities in fetal development through imaging Fetal blood sampling = Obtains a small sample of fetal blood, typically from the umbilical cord, to detect genetic or chromosomal abnormalities as well as blood disorders or infections</p> Signup and view all the answers

Flashcards

What are genetic disorders?

A disease caused by abnormalities in genes or chromosomes.

What are genes?

Building blocks of heredity, passed from parent to child.

What is DNA?

Molecule containing an individual's genes, found in cells.

What are nucleic acids?

Made of different combinations of adenine, thymine, cytosine, and guanine.

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What is the role of proteins in cells?

They move molecules, build structures and break down toxins.

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What is a mutation?

A change in a gene or genes.

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What is the effect of mutation on protein production?

Can change gene’s instructions, leading to improperly working or missing protein.

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What is a genetic disorder?

A medical condition caused by a gene mutation.

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What is gene mutation?

Condition one can inherit from one or both parents.

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How many does each person has pairs of chromosomes?

Each parent provides one set of 23 chromosomes to offspring.

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What are sex chromosomes?

They distinguish males from females: X and Y.

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What is the difference between male and female chromosomes?

Females have two X chromosomes; males have one X and one Y.

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What are mutations in sex chromosomes?

Mutations in sex chromosomes that can affect sexes differently.

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What is an autosomal recessive trait?

Trait needing two copies of a mutated gene to be inherited.

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What is genetic 'carriers'?

They do not generally experience symptoms but can pass the trait to children.

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What does inherited mean?

Genetic conditions passed from parents to children.

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What causes some genetic disorder?

Mutations that occur during development of egg, sperm, or embryo.

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Gene mutation

Permanent alteration in the DNA sequence that makes up a gene.

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What are hereditary mutations?

Mutations inherited from a parent, present throughout life in every cell.

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What are acquired mutations?

Mutations that occur during a person's life, present only in certain cells.

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What is Single-gene disorder?

Mutation affects one gene, like sickle cell anemia.

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What is Chromosomal disorders?

Disorder where chromosomes are missing or changed, like Down syndrome.

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What is Complex disorders?

Mutation in two or more genes, plus lifestyle/ environment, like colon cancer.

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What are genetic tests?

Tests on blood/tissue to find genetic disorders.

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What is the purpose of genetic tests?

Finding diseases in unborn babies, carriers, screening embryos.

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What are physical characteristics examined?

Distinctive features suggesting a genetic disorder.

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What measurements during physical examination?

Measurements like head circumference.

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Specialized examinations?

Neurological or ophthalmologic exams.

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What can imaging studies see?

Imaging (MRI) to see structures inside the body.

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What is Personal Medical History?

Health information providing clues to a genetic diagnosis.

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What included Personal Medical History?

Health, hospitalizations, and medical test results.

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What is Family Medical History?

Health information of family members critical for diagnosing.

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Who will ask relatives health conditions?

Doctor/counselor asks about health conditions in relatives.

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What does diagnosis for genetic disorders?

Molecular, chromosomal, and biochemical genetic testing to diagnose.

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What is Prenatal diagnosis?

Prenatal diagnosis to detect abnormalities via ultrasound.

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What is Huntington's Disease (HD)?

Degeneration of nerve cells in brain and affects central nerve system.

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How develop the 'Huntington's Disease (HD)'?

Children have a 50% chance of developing it from their parents.

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What are the aims of Treatment of 'Huntington's Disease (HD)'?

Aims limits the course of the disease and HD typically shows itself when the individual is between 30 and 40-years old however, rare forms begin in childhood.

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What causes Down syndrome?

Down syndrome results from an extra copy of genes on chromosome 21.

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What is Trisomy 21?

Three copies of chromosome 21 instead of two.

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Mosiac Down Syndrome

Mosiac Down syndrome, This mosaic of normal and abnormal cells is caused by abnormal cell division after fertilization.

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Translocation Down Syndrome

Part of chromosome 21 becomes attached to another chromosome and these has the usual two copies of chromosome 21, but they also have additional material from chromosome 21 attached to the translocated chromosome.

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What is the Duchenne Muscular Dystrophy?

Duchenne Muscular Dystrophy (DMD) affect muscles.

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How fatigue and wheaks when affected Duchenne Muscular Dystrophy (DMD)?

Fatigue and weakness in the legs, later progresses to upper body.

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Which symptoms will happened when person has the Duchenne Muscular Dystrophy?

Condition that affects mostly boys with symptoms such as heart and respiratory difficulties, deformity of the chest and back, and potential mental retardation.

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What are the treatment options?

Most revolve treating symptoms to improve patient quality of life.

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What is gen therapy?

Introducing a healthy gene is introduced to a patient.

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Study Notes

Genetic Disorders

  • Genetic diseases occur when a person has one or more abnormal, missing, extra, inactivated, or overly active genes, leading to a medical condition.

Understanding Genetic Disorders

  • Genes serve as the building blocks of heredity and are passed from parent to child.
  • Genes reside within cells of all organisms, present in a large molecule called deoxyribonucleic acid (DNA).
  • DNA holds instructions for making proteins.
  • DNA comprises different combinations of four nucleic acids: adenine, thymine, cytosine, and guanine, arranged in varying lengths.
  • Proteins perform most of the work within cells.
  • Proteins transport molecules, build structures, break down toxins, and perform maintenance tasks.
  • Human cells typically contain 23 pairs of chromosomes.
  • In each pair of chromosomes, one comes from the father and the other from the mother.
  • Mutation, or change, can occur in a gene or genes.
  • Mutation alters a gene's instructions for making a protein, which causes the protein to malfunction or become entirely absent.
  • A medical condition may arise due to this.
  • A person can inherit a gene mutation from one or both parents.

Heredity of Genetic Disorders

  • A person's DNA exists within two sets of chromosomes, with each parent contributing one set of 23 chromosomes, totaling 23 pairs of chromosomes.
  • X and Y chromosomes, known as sex chromosomes, differentiate males from females.
  • Females possess a pair of X chromosomes, while males possess one X and one Y chromosome.
  • Genetic conditions can arise from mutations in sex chromosomes, affecting males and females differently.
  • Individuals with only one copy of a mutated gene typically do not experience disease symptoms but are termed "carriers," capable of passing the trait to their offspring.
  • Genetic conditions are commonly inherited, transmitted from parents to children.
  • Some genetic disorders stem from mutations occurring during the development of the egg, sperm, or embryo, even without a family history of the disorder.

Gene Mutation and Types

  • A gene mutation signifies a permanent alteration in the DNA sequence constituting a gene.
  • Types of gene mutations:
    • Acquired mutations: Occur during a person's lifetime and are present only in specific cells, not throughout the body.
    • Hereditary mutations: Inherited from a parent and are present throughout a person's life in virtually every cell in the body.

Hereditary Mutation

  • Hereditary mutations are inherited from a parent and are in virtually every cell
  • Also known as Germ line mutations they are in the parents egg and sperm cells
  • The fertilized cell after union of the sperm and egg receive DNA from both parents
  • If the DNA has a mutation, the growing child will have the mutation in each of their cells

Acquired Mutation

  • Acquired mutations occur sometime during a persons life
  • They are only present in certain cells
  • Environmental factors like UV radiation can cause them
  • They can also occur if a mistake is made during DNA copying in cell division
  • Acquired mutations in Somatic cells (not sperm & egg) cannot be passed on to the next generation.

Types of Genetic Disorders

  • Single-gene disorders: Mutation affects one gene; Sickle cell anemia is an example.
  • Chromosomal disorders: Chromosomes (or parts of chromosomes) are missing or changed.
    • Chromosomes hold our genes.
    • Down syndrome is a chromosomal disorder.
  • Complex disorders: Mutations in two or more genes.
    • Lifestyle and environment play a role; Colon cancer is an example.

Diagnosing Genetic Disorders

  • Genetic tests involve blood and tissue analysis to detect genetic disorders.
  • Purposes of these tests
    • Finding genetic diseases in unborn babies
    • Determining if individuals carry a disease gene that can be passed to children
    • Screening embryos for disease
    • Testing adults for genetic diseases before symptoms manifest
    • Diagnosing individuals with disease symptoms
    • Determining the optimal medicine type and dosage for a patient

Physical Examination

  • Distinctive facial features sometimes indicate a diagnosis of a genetic disorder.
  • Geneticists conduct thorough physical examinations, measuring head circumference, distance between eyes, and length of arms and legs.
  • Specialized examinations, such as neurological or ophthalmologic exams, may be performed.
  • Imaging studies (X-rays, CT scans, MRI) visualize internal body structures.

Personal Medical History

  • An individual's health information, traced back to birth, gives indications on a genetic diagnosis.
  • Medical history encompasses past health problems, hospitalizations, surgeries, allergies, medications, and prior medical or genetic testing results.

Family Medical History

  • Genetic conditions often run in families, making family health information a critical diagnostic tool.
  • Doctors or genetic counselors inquire about health conditions in parents, siblings, children, and extended relatives.
  • This gives information about the diagnosis and inheritance pattern of genetic conditions.

Labratory Tests

  • Genetic testing can be molecular, chromosomal, and biochemical - allowing the diagnosis of disorders.
  • Other lab tests can assess the levels of certain substances in blood and urine, suggesting diagnosis.

Prenatal Diagnosis

  • Prenatal diagnosis can detect fetal abnormalities via ultrasound or testing for characteristic substances through invasive procedures like amniocentesis, which involves inserting probes or needles into the uterus.

Huntington's Disease (HD)

  • HD involves degeneration of nerve cells in brain and central nervous system.
  • It is an autosomal dominant hereditary condition, with a 50% chance of children developing and passing it on if a parent has it.
  • Treatment aims to limit the course of the disease, typically showing itself between ages 30-40, with rare forms beginning in childhood.
  • Symptoms include uncontrolled movement (chorea), difficulty swallowing, behavioral changes, balance difficulty, and memory, speech, and cognitive loss.

Down Syndrome

  • Characterized as a common chromosomal abnormality where an extra copy of genes occur on chromosome 21.
  • Occurs in approximately 1 in 1000 newborns, particularly in older expectant mothers.
  • Although pre-natal testing can detect it, the babies affected typically show symptoms at birth.
    • Decreased muscle tone in the face, developmental delays, and heart and digestive system defects

Down Syndrome - Etiology

  • Trisomy 21: The child possesses three copies of chromosome 21 in all cells due to abnormal cell division during sperm or egg cell development.
  • Mosaic Down Syndrome: Children have a mix of normal and abnormal cells (extra copy of chromosome 21) because of abnormal cell division after fertilization.
  • Translocation Down Syndrome: Part of chromosome 21 attaches (translocates) onto another chromosome before or at conception. These children have the usual two copies of chromosome 21 plus additional material from the translocated chromosome.

Duchenne Muscular Dystrophy

  • Symptoms of Duchenne Muscular Dystrophy show before age six.
  • The condition causes fatigue, muscle weakness (starts in legs), progresses to the upper body causing wheelchair use by age 12.
  • Mostly affects boys
  • Symptoms are heart and respiratory difficulties, chest/deformity and mental retardation.

Treatment

  • Most treatment options address symptoms to improve patient quality of life.
  • Gene therapy introduces a healthy gene to a patient and alleviates defects caused by a faulty gene.
  • Gene therapy has issues delivering genes to the appropriate organ or tissue.

Prognosis

  • Not all genetic disorders are fatal
  • No known cures for genetic diorders exist
  • Genetic disorders like Down syndrome affect stages of development.
  • Other genetic diorders like muscular dystrophy result in purely physical symptoms
  • Some disorders, such as Huntington's Disease, show no signs until adulthood

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