What is the pathology of Huntington disease?

Updated: Dec 23, 2019
  • Author: Thomas J Montine, MD, PhD; Chief Editor: Adekunle M Adesina, MD, PhD  more...
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Answer

Answer

Huntington disease (HD) is unique among the dementing illnesses in that it is always caused by a defect in a single gene, HTT. It is almost always autosomal dominant and, essentially, no sporadic form exists, although rare de novo mutations exist. HD is caused by a trinucleotide (CAG) repeat expansion in HTT that causes an elongated polyglutamine repeat in the Huntington protein. [24] Clinically, HD is primarily characterized by its characteristic choreiform movement disorder, but it also includes psychiatric disturbances and, ultimately, dementia. [25] No cure exists.

Pathologically, HD is characterized primarily by neuronal loss, atrophy, and gliosis of the caudate and putamen beginning in the anterior medial caudate. As the disease progresses, this neuronal loss, atrophy, and gliosis may involve multiple brain regions. Immunohistochemical staining against polyglutamine reveals intraneuronal inclusions, although this finding is usually not necessary for the diagnosis. Pathologic staging is performed by assessing the amount of atrophy, neuronal loss, and gliosis in the caudate and putamen. [26]


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