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In a wrap up of Huntington's, Chorea.

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I'd like to show you FDG, fluorodeoxyglucose,

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positron emission tomography.

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Now, as you know,

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Huntington's Chorea is a genetic disorder

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inherited as an autosomal dominant.

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The gene is called the interesting transcript

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or IT-15 gene found on chromosome four.

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The gene product, however,

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is expressed in Alzheimer's disease

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and in Pick's disease.

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As you know,

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it consists of a trinucleotide syndrome in which

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cytosine, adenine, and guanine repeat and the number

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of repeats not only determines the clinical

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symptomatology when it presents

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in life, in other words,

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greater number of repeats earlier presentation

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but also has an effect on the metabolic MR

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manifestations, including hypoperfusion and

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hypometabolism of the caudoputaminal region.

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I also want to remind you of the phenomenon

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of anticipation in which the phenotypical

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manifestation or the severity of the disease

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increases with each generation.

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So, let's look at a very gross example of somebody

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with Huntington's Chorea who has 57 CAG repeats.

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We have an axial T2 and an axial PD.

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Look at the diminutive size of the caudate.

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Look at the narrow configuration of

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the putamen from side to side.

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It virtually looks like a slit on either side.

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And this can go on to frank necrosis

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with cystic degeneration.

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Not surprising is the positron emission tomography

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study which demonstrates with fluorodeoxyglucose

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profound hypometabolism.

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Look at that gray matter structure compared to the

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cortical gray matter in the frontal

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region on both sides.

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The caudate nuclei are not only severely atrophic,

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they're severely hypometabolic.

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And on perfusion imaging, we're hypoperfused.

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Huntington's Chorea,

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an autosomal dominant inherited

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condition causing Chorea.