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|Prompt=A 36 year old woman presents to her physician for the gradual onset of uncontrolled spastic movements. She reports having begun experiencing mood disturbances and difficulty performing her job at work 3 months prior to the onset of her movement disorder began. Further questioning reveals that her father died of a neurodegenerative condition at the age of 50. The patient has researched her likely condition on the internet and is most concerned about having passed the trait onto her kids. She inquires about genetic testing. Which of the following would one expect to find in this patient? | |Prompt=A 36 year old woman presents to her physician for the gradual onset of uncontrolled spastic movements. She reports having begun experiencing mood disturbances and difficulty performing her job at work 3 months prior to the onset of her movement disorder began. Further questioning reveals that her father died of a neurodegenerative condition at the age of 50. The patient has researched her likely condition on the internet and is most concerned about having passed the trait onto her kids. She inquires about genetic testing. Which of the following would one expect to find in this patient? | ||
|Explanation=Huntington's disease (HD) is a neurodegenerative genetic disorderthat affects muscle coordination and leads to cognitive decline andpsychiatric problems. It typically becomes noticeable in mid-adult life. HD is the most common genetic cause of abnormal involuntary writhing movements called chorea, which is why the disease used to be called Huntington's chorea. The Huntingtin gene provides the genetic information for a protein that is also called "huntingtin". Expansion of a CAG triplet repeat stretch within the Huntingtin gene results in a different (mutant) form of the protein, which gradually damages cells in the brain, through mechanisms that are not fully understood. The disease is inherited in an autosomal dominant manner and displays genetic anticipation: earlier onset of disease in successive generations. This anticipation is caused by expansion of the repeat segment, which increases disease severity. Huntington’s disease is uniformly fatal. | |Explanation=Huntington's disease (HD) is a neurodegenerative genetic disorderthat affects muscle coordination and leads to cognitive decline andpsychiatric problems. It typically becomes noticeable in mid-adult life. HD is the most common genetic cause of abnormal involuntary writhing movements called chorea, which is why the disease used to be called Huntington's chorea. The Huntingtin gene provides the genetic information for a protein that is also called "huntingtin". Expansion of a CAG triplet repeat stretch within the Huntingtin gene results in a different (mutant) form of the protein, which gradually damages cells in the brain, through mechanisms that are not fully understood. The disease is inherited in an autosomal dominant manner and displays genetic anticipation: earlier onset of disease in successive generations. This anticipation is caused by expansion of the repeat segment, which increases disease severity. Huntington’s disease is uniformly fatal. | ||
'''Wiki-mnemomic:''' You hunt animals and put them in the '''CAG'''e: Huntington Disease '''CAG''' | |||
'''Educational Objective:''' Huntington's disease is caused by a CAG repeat expansion. | |||
'''References:''' First Aid page 90,92,439 | |||
|AnswerA=Loss of function mutation | |AnswerA=Loss of function mutation | ||
|AnswerAExp=Incorrect - Huntington’s disease is caused by a trinucleotide expansion | |AnswerAExp=Incorrect - Huntington’s disease is caused by a trinucleotide expansion | ||
Revision as of 01:06, 8 September 2013
| Author | PageAuthor::William J Gibson |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Genetics |
| Sub Category | SubCategory::Neurology |
| Prompt | [[Prompt::A 36 year old woman presents to her physician for the gradual onset of uncontrolled spastic movements. She reports having begun experiencing mood disturbances and difficulty performing her job at work 3 months prior to the onset of her movement disorder began. Further questioning reveals that her father died of a neurodegenerative condition at the age of 50. The patient has researched her likely condition on the internet and is most concerned about having passed the trait onto her kids. She inquires about genetic testing. Which of the following would one expect to find in this patient?]] |
| Answer A | AnswerA::Loss of function mutation |
| Answer A Explanation | AnswerAExp::Incorrect - Huntington’s disease is caused by a trinucleotide expansion |
| Answer B | AnswerB::Expansion of CAA repeats |
| Answer B Explanation | AnswerBExp::ncorrect - This repeat is expanded in Friedreich’s ataxia |
| Answer C | AnswerC::Expansion of CAG repeats |
| Answer C Explanation | AnswerCExp::Correct - See Explanation. |
| Answer D | AnswerD::Expansion of CGG repeats |
| Answer D Explanation | AnswerDExp::Incorrect - This repeat is expanded in Fragile X Syndrome |
| Answer E | AnswerE::Expansion of CTG repeats |
| Answer E Explanation | AnswerEExp::Incorrect - This repeat is expanded in Myotonic dystrophy |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::Huntington's disease (HD) is a neurodegenerative genetic disorderthat affects muscle coordination and leads to cognitive decline andpsychiatric problems. It typically becomes noticeable in mid-adult life. HD is the most common genetic cause of abnormal involuntary writhing movements called chorea, which is why the disease used to be called Huntington's chorea. The Huntingtin gene provides the genetic information for a protein that is also called "huntingtin". Expansion of a CAG triplet repeat stretch within the Huntingtin gene results in a different (mutant) form of the protein, which gradually damages cells in the brain, through mechanisms that are not fully understood. The disease is inherited in an autosomal dominant manner and displays genetic anticipation: earlier onset of disease in successive generations. This anticipation is caused by expansion of the repeat segment, which increases disease severity. Huntington’s disease is uniformly fatal.
Wiki-mnemomic: You hunt animals and put them in the CAGe: Huntington Disease CAG Educational Objective: Huntington's disease is caused by a CAG repeat expansion. References: First Aid page 90,92,439 |
| Approved | Approved::Yes |
| Keyword | |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |