WBR0369
Author | [[PageAuthor::Gonzalo A. Romero, M.D. [1]]] |
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Exam Type | ExamType::USMLE Step 1 |
Main Category | MainCategory::Biochemistry, MainCategory::Pathology, MainCategory::Pathophysiology |
Sub Category | SubCategory::Neurology |
Prompt | [[Prompt::A research lab develops a new knock-in mouse model with a chimeric mouse/human exon containing 140 CAG repeats inserted into a gene located on the short arm of chromosome 4. The mice are grown and observed for 18 months. All mice develop increased locomotor activity and abnormal posturing around 1 month of age, followed by hypoactivity at 4 months and gait abnormalities at 1 year. Which of the following neurochemical changes is associated with this syndrome?]] |
Answer A | AnswerA::Decreased norepinephrine, Decreased serotonin, Decreased dopamine |
Answer A Explanation | [[AnswerAExp::These are the neurotransmitter changes associated in depression]] |
Answer B | AnswerB::Increased norepinephrine, Increased serotonin, Increased dopamine |
Answer B Explanation | [[AnswerBExp::This is seen in schizophrenia]] |
Answer C | AnswerC::Increased acetylcholine, Increased serotonin, Decreased dopamine |
Answer C Explanation | [[AnswerCExp::These changes are seen in parkinson’s disease]] |
Answer D | AnswerD::Decreased GABA, Decreased acetylcholine, Increased dopamine |
Answer D Explanation | AnswerDExp::These changes are associated with Huntington disease. |
Answer E | AnswerE::Increased norepinephrine, Decreased GABA, Decreased serotonin |
Answer E Explanation | [[AnswerEExp::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 in the huntingtin gene. The disease is characterized by caudate atrophy leading to a decrease in GABA and acetylcholine, and an increase in dopamine. |
Approved | Approved::Yes |
Keyword | WBRKeyword::Huntington's disease, WBRKeyword::GABA, WBRKeyword::Serotonin, WBRKeyword::CAG, WBRKeyword::Trinucleotide repeat disorders, WBRKeyword::caudate |
Linked Question | Linked:: |
Order in Linked Questions | LinkedOrder:: |