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  1. #1
    pathologyguy is offline Junior Member
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    mitochondrial enzyme

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    A young adult has progressive intellectual deterioration, weakness, ataxia, and seizures. Reference laboratory tests demonstrate an abnormality of an important mitochondrial enzyme. From which of the following diseases is this person most likely suffering?

    A. Adrenoleukodystrophy
    B. Central pontine myelinolysis
    C. Krabbe's disease
    D. Leigh's disease
    E. Metachromatic leukodystrophy

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    Asclepius1 is offline Ultimate Member 537 points
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    My guess is C. Krabbe's disease

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    pathologyguy is offline Junior Member
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    Re: mitochondrial enzyme

    Quote Originally Posted by pathologyguy
    A young adult has progressive intellectual deterioration, weakness, ataxia, and seizures. Reference laboratory tests demonstrate an abnormality of an important mitochondrial enzyme. From which of the following diseases is this person most likely suffering?

    A. Adrenoleukodystrophy
    B. Central pontine myelinolysis
    C. Krabbe's disease
    D. Leigh's disease
    E. Metachromatic leukodystrophy
    The correct answer is D. Leigh's disease, also known as subacute necrotizing encephalomyelopathy, is a very rare disease that most physicians will never encounter in real life. However, it may show up on the USMLE because it is one of the few examples of diseases involving defects in the mitochondrial DNA rather than the chromosomal DNA. The specific defective enzyme, in at least some cases, is cytochrome oxidase, one of the components of the electron transport system. Muscle and brain are particularly affected. Patients have the presentation described in the question and typically die within several years.
    Adrenoleukodystrophy (choice A) is an X-linked disease with abnormal lipid metabolism leading to demyelination in the CNS.

    Central pontine myelinolysis (choice B) is characterized by demyelination of the pons (especially the basis pontis) seen after overlying rapid correction of hyponatremia.

    Krabbe's disease (choice C) is an autosomal recessive accumulation of cerebrosides in histiocytes in the CNS.

    Metachromatic leukodystrophy (choice E) is an autosomal recessive accumulation of sphingolipids in the CNS and elsewhere.

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