WBR0369

Author	[[PageAuthor::Gonzalo A. Romero, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Biochemistry, MainCategory::Pathology, MainCategory::Pathophysiology
Sub Category	SubCategory::Neurology
Prompt	[[Prompt::A neurobiologist is trying to determine different neurobiochemical changes in synaptic connections within different monkey brains. Several animal models are created to mimic diverse human pathologic conditions. A neurogenerative disorder is created in rats by introducing multiple CAG repeats s in their genetic sequence leading to caudate damage, and demented monkeys. Which of the following neurochemical changes is associated with this disease?]]
Answer A	AnswerA::Decreased NE, 5-HT and DA
Answer A Explanation	[[AnswerAExp::Incorrect. These are the neurotransmitter changes associated in depression]]
Answer B	AnswerB::Increased DA
Answer B Explanation	[[AnswerBExp::Incorrect. This is seen in schizophrenia]]
Answer C	AnswerC::Decreased DA, increased 5-HT and increased Ach
Answer C Explanation	[[AnswerCExp::Incorrect. These changes are seen in parkinson’s disease]]
Answer D	AnswerD::Decreased GABA and Ach, increased DA
Answer D Explanation	[[AnswerDExp::Correct. These changes are associated with Huntington disease.]]
Answer E	AnswerE::Increased NE, decreased GABA and 5-HT
Answer E Explanation	[[AnswerEExp::Incorrect. These neurotransmitter changes are seen in anxiety]]
Right Answer	RightAnswer::D
Explanation	[[Explanation::This animal model is trying to develop Huntington disease in the monkeys, which is caused by a trinucleotide repeat (CAG), which caused damage to the caudate nucleus. Biochemically; human brains affected with this autosomal dominant disease have decreased GABA and Ach, increased DA. Educational Objective: Huntington is an autosomal dominant disease caused by a CAG trinucleotide expansion, which causes structural damage to the caudate. The neurotransmitter changes seen are Decreased GABA and Ach, increased DA References: First Aid 2013 page 461 Educational Objective: References: ]]
Approved	Approved::No
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