Trinucleotide Repeat Expansion Diseases
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Questions and Answers

Quale de iste trinucleotide repeat expansion diseases es associate con un mutation in le gene FMR1?

  • Spinocerebellar ataxia type 3
  • Myotonic dystrophy
  • Huntington
  • Syndrome de Fragile X (correct)

    • Quale trinucleotide repeat expansion disease es characterisate per un expansion del trinucleotide CAG?

  • Myotonic dystrophy
  • Syndrome de Fragile X
  • Huntington (correct)
  • Spinocerebellar ataxia type 3

    • Quale de iste trinucleotide repeat expansion diseases es associate con un expansion del trinucleotide CTG?

  • Spinocerebellar ataxia type 3
  • Myotonic dystrophy (correct)
  • Syndrome de Fragile X
  • Huntington

    • Quale de iste trinucleotide repeat expansion diseases es characterisate per un expansion del trinucleotide CAG/CTG?

    <p>Spinocerebellar ataxia type 3 (B)</p> Signup and view all the answers

    Quale de iste trinucleotide repeat expansion diseases es associate con un mutation que resulta in un deficiency de proteina FMRP?

    <p>Syndrome de Fragile X (B)</p> Signup and view all the answers

    Quale de iste trinucleotide repeat expansion diseases es characterisate per un accumulation anormal de proteina huntingtin?

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

    Quale de iste trinucleotide repeat expansion diseases es associate con un accumulation anormal de RNA e proteina associate con le genes DMPK o CNBP?

    <p>Myotonic dystrophy (C)</p> Signup and view all the answers

    Quale de iste trinucleotide repeat expansion diseases es characterisate per degeneration del cerebello?

    <p>Spinocerebellar ataxia type 3 (C)</p> Signup and view all the answers

    Flashcards

    Maladie de répétition de trinucleotides

    Une maladie génétique causée par une expansion anormale de répétitions de séquences de trois nucléotides dans un gène.

    Expansion de répétitions

    Augmentation du nombre de fois qu'une séquence de trinucleotides est répétée dans un gène.

    Gènes affectés

    Certains gènes spécifiques sont souvent impliqués dans les maladies de répétition de trinucleotides.

    Huntington

    Une maladie neurologique causée par une expansion de CAG dans le gène HTT.

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    Ataxie spinocérébelleuse

    Groupe de troubles liés à l'équilibre causés par des répétitions de trinucleotides.

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    Anticipation

    Phénomène où les symptômes apparaissent plus tôt et sont plus graves dans les générations suivantes.

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    Terme trinucleotidique

    Séquence d'ADN de trois nucléotides consécutifs.

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    Mutations

    Modifications de la séquence d'ADN qui peuvent causer des maladies.

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    Study Notes

    Trinucleotide Repeat Expansion Diseases

    • Group of genetic diseases with expanded nucleotide repeats (3 base pairs).
    • Characterized by mutations; C and G nucleotides are the primary loci.
    • Disease mechanism involves loss-of-function (transcriptional silencing) or toxic gain-of-function (mRNA/protein level).
    • Risk factors include family history.
    • Complications include disease anticipation (often severe, earlier onset).

    Fragile X Syndrome

    • X-linked disorder; intellectual disability, specific facial features, enlarged testicles (macroorchidism).
    • Inherited defect in the FMR1 gene, leading to trinucleotide expansion.
    • Expansion results in methylation and reduced FMRP (familial mental retardation protein) synthesis.
    • This leads to clinical phenotype.

    Huntington's Disease

    • Autosomal dominant, neurodegenerative disease; characterized by chorea (involuntary movements), dementia.
    • Average age of onset is 40.
    • Death of medium spiny striatal neurons (GABAergic) disrupts normal dopamine and glutamate signaling, triggering hyperkinetic movements.
    • Cortical cell death leads to cognitive impairment.
    • Caused by trinucleotide CAG repeats in the HTT gene.
    • Intermediate repeat number (27-35) is uncommonly associated with disease and incomplete penetrance.
    • Repeat numbers of 36-39 show incomplete penetrance due to variable expression levels.
    • Repeat above 40 show full penetrance, and increasing repeat numbers lead to increasingly lower age of onset.
    • HTT protein aggregation, reduced mitochondrial oxidative stress protection genes, and altered levels of brain-derived neurotrophic factors are also possible pathogenic components.
    • Complications include depression and suicide risk.
    • Signs and symptoms include motor symptoms like hypotonia, hyperreflexia, chorea, athetosis and psychiatric symptoms like apathy, irritability, delusions.

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    Related Documents

    Trinucleotide Repeat Expansion Diseases PDF

    Description

    Explora le enfermedades genetic con expansion de trinucleotidos. Illustra le mechanismo de mutation, comprehendente condiciones como le Sindrome de Fragile X e le Maladia de Huntington. Unde disposita le complicationes e factores de risco implicate.

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