WBR0143: Difference between revisions

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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor={{Rim}} (Edited by Will Gibson)
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Genetics
|MainCategory=Genetics
Line 20: Line 20:
|MainCategory=Genetics
|MainCategory=Genetics
|SubCategory=General Principles
|SubCategory=General Principles
|Prompt=A 17-year-old male was brought by his parents for an annual checkup.  The patient’s face and jaw appear to be larger than normal.  The patient is slow in answering the physician's questions and sounded younger than his age. A review of his past medical history reveals documented decreased cognition level.  The patient’s condition is most likely caused by trinucleotide repeats of which of the following?
|Prompt=A 17-year-old male is brought by his parents for an annual checkup.  The patient’s face and jaw appear to be larger than normal.  The patient is slow in answering the physician's questions and sounds younger than his age. A review of his past medical history reveals documented decreased cognition function.  The patient’s condition is most likely caused by trinucleotide repeats of which of the following?
|Explanation=The patient is suffering from mental retardation and enlarged face and jaw that are consistent with [[Fragile X syndrome]].  Fragile X syndrome is a [[syndrome]] of [[X-linked]] [[mental retardation]].  Boys with the syndrome may have large testicles ([[macroorchidism]]), [[prognathism]], [[hypotonia]] and [[autism]], and a characteristic but variable face with large ears, long face, high-arched [[palate]], [[gynecomastia]], and [[malocclusion]]. Additional abnormalities may include [[lordosis]], heart defect, [[pectus excavatum]], [[flat feet]], shortening of the tubular bones of the hands, and joint laxity.
|Explanation=The patient is suffering from mental retardation and enlarged face and jaw that are consistent with [[Fragile X syndrome]].  Fragile X syndrome is a [[syndrome]] of [[X-linked]] [[mental retardation]].  Boys with the syndrome may have large testicles ([[macroorchidism]]), [[prognathism]], [[hypotonia]] and [[autism]], and a characteristic but variable face with large ears, long face, high-arched [[palate]], [[gynecomastia]], and [[malocclusion]]. Additional abnormalities may include [[lordosis]], heart defect, [[pectus excavatum]], [[flat feet]], shortening of the tubular bones of the hands, and joint laxity.


Educational objective:  [[Fragile X syndrome]] is caused by CGG repeats.
[[File:202px-Fragile_x_syndrom.png|center|200px]]
 
Example of facial characteristics of patient with Fragile X.
 
'''Educational Objective:''' Fragile X syndrome is caused by expansion of CGG repeats in the FMR1 gene on the X Chromosome.
 
'''References:'''  First Aid 2012 page 92
|AnswerA=CAG
|AnswerA=CAG
|AnswerAExp=CAG repeats are seen in [[Huntington’s disease]].
|AnswerAExp=CAG repeats are seen in [[Huntington’s disease]]. '''Wiki-mnemomic:''' You hunt animals and put them in the '''CAG'''e: Huntington Disease '''CAG'''
|AnswerB=GAA
|AnswerB=GAA
|AnswerBExp=GAA repeats are seen in [[Friedreich's ataxia]].
|AnswerBExp=GAA repeats are seen in [[Friedreich's ataxia]].
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|AnswerCExp=GGA repeats are not specific to a disease.
|AnswerCExp=GGA repeats are not specific to a disease.
|AnswerD=CTG
|AnswerD=CTG
|AnswerDExp=CTG repeats are seen in [[myotonic dystrophy]].
|AnswerDExp=CTG repeats are seen in [[Myotonic dystrophy]].
|AnswerE=GGG
|AnswerE=GGG
|AnswerEExp=CGG repeats are seen in [[Fragile X syndrome]]. The patient is suffering from [[mental retardation]] and enlarged face and jaw that are consistent with Fragile X syndrome.
|AnswerEExp=CGG repeats are seen in [[Fragile X syndrome]]. The patient is suffering from [[mental retardation]] and enlarged face and jaw that are consistent with Fragile X syndrome.
|RightAnswer=E
|RightAnswer=E
|Approved=No
|WBRKeyword=Mental retardation, Retardation, Repeat disorder, Nucleotide, Nucleotide repeat
|Approved=Yes
}}
}}

Revision as of 23:45, 5 October 2013
Author [[PageAuthor::Rim Halaby, M.D. [1] (Edited by Will Gibson)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Genetics
Sub Category SubCategory::General Principles
Prompt [[Prompt::A 17-year-old male is brought by his parents for an annual checkup. The patient’s face and jaw appear to be larger than normal. The patient is slow in answering the physician's questions and sounds younger than his age. A review of his past medical history reveals documented decreased cognition function. The patient’s condition is most likely caused by trinucleotide repeats of which of the following?]]
Answer A AnswerA::CAG
Answer A Explanation [[AnswerAExp::CAG repeats are seen in Huntington’s disease. Wiki-mnemomic: You hunt animals and put them in the CAGe: Huntington Disease CAG]]
Answer B AnswerB::GAA
Answer B Explanation [[AnswerBExp::GAA repeats are seen in Friedreich's ataxia.]]
Answer C AnswerC::GGA
Answer C Explanation AnswerCExp::GGA repeats are not specific to a disease.
Answer D AnswerD::CTG
Answer D Explanation [[AnswerDExp::CTG repeats are seen in Myotonic dystrophy.]]
Answer E AnswerE::GGG
Answer E Explanation [[AnswerEExp::CGG repeats are seen in Fragile X syndrome. The patient is suffering from mental retardation and enlarged face and jaw that are consistent with Fragile X syndrome.]]
Right Answer RightAnswer::E
Explanation [[Explanation::The patient is suffering from mental retardation and enlarged face and jaw that are consistent with Fragile X syndrome. Fragile X syndrome is a syndrome of X-linked mental retardation. Boys with the syndrome may have large testicles (macroorchidism), prognathism, hypotonia and autism, and a characteristic but variable face with large ears, long face, high-arched palate, gynecomastia, and malocclusion. Additional abnormalities may include lordosis, heart defect, pectus excavatum, flat feet, shortening of the tubular bones of the hands, and joint laxity.

Example of facial characteristics of patient with Fragile X.

Educational Objective: Fragile X syndrome is caused by expansion of CGG repeats in the FMR1 gene on the X Chromosome.

References: First Aid 2012 page 92
Educational Objective:
References: ]]

Approved Approved::Yes
Keyword WBRKeyword::Mental retardation, WBRKeyword::Retardation, WBRKeyword::Repeat disorder, WBRKeyword::Nucleotide, WBRKeyword::Nucleotide repeat
Linked Question Linked::
Order in Linked Questions LinkedOrder::
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