WBR0369: Difference between revisions
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|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? | |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? | ||
|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. | |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. | ||
|AnswerA=Decreased norepinephrine, Decreased serotonin, Decreased dopamine | |AnswerA=Decreased norepinephrine, Decreased serotonin, Decreased dopamine | ||
|AnswerAExp=These are the neurotransmitter changes associated in [[depression]] | |AnswerAExp=These are the neurotransmitter changes associated in [[depression]] | ||
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|AnswerE=Increased norepinephrine, Decreased GABA, Decreased serotonin | |AnswerE=Increased norepinephrine, Decreased GABA, Decreased serotonin | ||
|AnswerEExp=These neurotransmitter changes are seen in [[anxiety]] | |AnswerEExp=These neurotransmitter changes are seen in [[anxiety]] | ||
|EducationalObjectives=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. | |||
|References=First Aid 2013 page 461<br> | |||
Menalled LB, Sison JD, Dragatsis I, Zeitlin S, Chesselet MF. Time course of early motor and neuropathological anomalies in a knock-in mouse model of Huntington's disease with 140 CAG repeats. J Comp Neurol. 2003;465(1):11-26.<br> | |||
Crow TJ, Baker HF, Cross AJ, et al. Monoamine mechanisms in chronic schizophrenia: post-mortem neurochemical findings. Br J Psychiatry. 1979;134:249-56. | |||
|RightAnswer=D | |RightAnswer=D | ||
|Approved= | |WBRKeyword=Huntington's disease, GABA, Serotonin, CAG, Trinucleotide repeat disorders, caudate, | ||
|Approved=Yes | |||
}} | }} | ||
Revision as of 00:14, 3 August 2014
| 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 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:: |