Patterns of Genetic Inheritance-2
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Questions and Answers

What is the typical recurrence risk for unaffected parents when a new mutation occurs?

  • High
  • Low (correct)
  • Very high
  • Moderate

    • In which condition is the risk of new mutations associated with advanced paternal age?

  • Huntington disease
  • Sickle cell anemia
  • Neurofibromatosis
  • Achondroplasia (correct)

    • Which of the following conditions exemplifies delayed onset of symptoms despite gene inheritance?

  • Marfan syndrome
  • Ehlers-Danlos syndrome
  • Neurofibromatosis
  • Huntington disease (correct)

    • Which of the following best describes 'variable expressivity' in genetic conditions?

    <p>Same genotype showing different disease severity (A)</p> Signup and view all the answers

    What does it mean for a phenotype to be caused by variants at different gene loci?

    <p>Variants at different loci cause similar expressions (C)</p> Signup and view all the answers

    Which syndrome is known to have a single locus affecting multiple distinct phenotypes?

    <p>Marfan syndrome (C)</p> Signup and view all the answers

    How common are new mutations in achondroplasia cases?

    <p>7/8 of cases are caused by new mutations (C)</p> Signup and view all the answers

    Which of the following syndromes is a type of hereditary cancer syndrome?

    <p>Neurofibromatosis (D)</p> Signup and view all the answers

    What is a defining characteristic of autosomal dominant inheritance?

    <p>The disorder can skip generations. (B)</p> Signup and view all the answers

    What is the significance of non-penetrance in genetic inheritance?

    <p>It describes a situation where some individuals with a genetic variant do not express the associated phenotype. (C)</p> Signup and view all the answers

    In sex-influenced traits, which of the following statements is accurate?

    <p>Expression of the trait can differ between sexes based on genetics. (D)</p> Signup and view all the answers

    What does genetic heterogeneity imply in the context of genetic disorders?

    <p>Multiple genes can lead to the same disorder. (A)</p> Signup and view all the answers

    What does it mean for a trait to be influenced by anticipation?

    <p>The trait becomes more severe in each generation. (B)</p> Signup and view all the answers

    What is germline mosaicism?

    <p>A condition where some gametes carry a genetic mutation, while others do not. (D)</p> Signup and view all the answers

    Which of the following is true about adult-onset conditions?

    <p>Their manifestations are only visible during adulthood. (B)</p> Signup and view all the answers

    How does pleiotropy affect genetic traits?

    <p>It refers to multiple traits linked to a single gene. (D)</p> Signup and view all the answers

    Flashcards

    Non-penetrance

    A genetic variant associated with a specific trait or disease, but the individual doesn't exhibit the associated phenotype or condition.

    New mutation

    A situation where a genetic mutation occurs spontaneously in the germ cells (sperm or egg) of a parent, leading to the offspring inheriting the mutation even though neither parent carries it.

    Adult-onset conditions

    A condition where an individual inherits a disease gene but doesn't develop the disorder until later in life.

    Anticipation

    A phenomenon where the severity of a genetic disorder increases in successive generations.

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    Sex-influenced trait

    A genetic trait that is influenced by the sex of the individual.

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    Consanguinity

    A situation where an individual inherits the same gene variant from both parents, potentially leading to increased risk of certain diseases.

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    Heterogeniety

    A situation where multiple genes can cause the same phenotype, making it difficult to determine the specific gene responsible based on inheritance patterns alone.

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    Pleiotropy

    A single gene can influence multiple traits, leading to diverse and seemingly unconnected symptoms.

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    Recurrence Risk for New Mutations

    The risk of having a child with a genetic disorder when both parents are unaffected but carry a new mutation.

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    Late-Onset Disorders

    A situation where a person inherits a gene for a disorder but doesn't show symptoms until adulthood.

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    Variable Expressivity

    Different levels of severity of a disorder in individuals with the same genetic mutation.

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    Genetic Heterogeneity

    Multiple genes contributing to a single disorder, meaning different combinations of genes can cause the same condition.

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    Syndromes

    A condition where a single gene mutation can lead to diverse symptoms and features.

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    Paternal Age and New Mutations

    Advanced paternal age is associated with a higher risk of new mutations in offspring.

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    Study Notes

    Patterns of Genetic Inheritance-2

    • Lecture covers autosomal dominant inheritance and complicating factors like non-penetrance, new mutations, adult-onset conditions, consanguinity, and interaction.
    • Sex-limited/sex-influenced traits are also discussed, along with germline mosaicism, anticipation, heterogeneity, and pleiotropy.
    • Non-penetrance is when an individual has a disease-causing gene variant but does not show the associated phenotype or condition. This can "skip" generations. Retinoblastoma is an example.
    • Autosomal dominant inheritance with sex-limited/sex-influenced traits: Males with one recessive allele will express the trait; females need two recessive alleles to express the same trait. Gene expression can be limited to specific sexes
    • New mutation: A change in the egg or sperm that causes the affected individual to be the first in their family to have that condition. Recurrence risk for unaffected parents is low. Achondroplasia is an example of a disorder associated with advanced paternal age.
    • Late-onset traits: Diseases that appear in adulthood instead of childhood or at birth. Huntington disease and many hereditary cancer syndromes are examples.
    • Variable expressivity: The severity of a genetic disorder can differ among individuals with the same genotype. Neurofibromatosis (NF1, NF2, NF3) and Treacher Collins syndrome are examples.
    • Locus heterogeneity: Variants at different gene loci can cause similar or identical phenotypes for a disorder or disease. Ehler Danlos Syndromes, hereditary deafness, retinitis pigmentosa, and tuberous sclerosis are examples.
    • Pleiotropy: A single locus can be responsible for a number of diverse and seemingly unrelated phenotypic effects. Marfan syndrome is an example.

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    The Patterns of Genetic Inheritance-2 PDF

    Description

    Explore the complexities of autosomal dominant inheritance in this quiz. Learn about factors such as non-penetrance, new mutations, and sex-limited traits that influence genetic expression. Test your knowledge on various inheritance patterns and associated disorders.

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