WBR0321: Difference between revisions

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|MainCategory=Biochemistry
|MainCategory=Biochemistry
|SubCategory=General Principles
|SubCategory=General Principles
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|MainCategory=Biochemistry
|MainCategory=Biochemistry
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|MainCategory=Biochemistry
|MainCategory=Biochemistry
|SubCategory=General Principles
|SubCategory=General Principles
|Prompt=A patient 5-year-old male is diagnosed with a characterized by the deficiency of enzyme X, as shown in the image below. Which of the following is most likely to be a clinical feature of this patient's condition?
|Prompt=A 5-year-old boy is diagnosed with a disorder characterized by the deficiency of enzyme X. The enzyme is an essential component of the pathway shown below. Which of the following is most likely to be a clinical feature of this patient's condition?


[[Image:WBR0321.png|500px]]
[[Image:WBR0321.png|500px]]
|Explanation=The patient has adenosine deaminase deficiency, a common cause of severe combined immunodeficiency (SCID). The disease is an X-linked disorder characterized by B cell and T cell deficiency. Accordingly, patients present with recurrent infections, thymic aplasia, and loss of germinal centers on lymph node biopsy.
|Explanation=The patient has adenosine deaminase deficiency, a common cause of severe combined immunodeficiency (SCID). The disease is an X-linked disorder characterized by B cell and T cell deficiency. Accordingly, patients present with recurrent infections, thymic aplasia, and loss of germinal centers on lymph node biopsy.


Educational Objective: Adenosine deaminase deficiency is a common cause of SCID.
|AnswerA=Delayed separation of umbilical cord
|AnswerA=Delayed separation of umbilical cord
|AnswerAExp=Leukocyte adhesion deficiency (type I) is due to a defect in LFA-1 integrin. Patients typically present with recurrent bacterial infections with no pus formation and delayed separation of the umbilical cord.
|AnswerAExp=Leukocyte adhesion deficiency (type I) is due to a defect in LFA-1 integrin. Patients typically present with recurrent bacterial infections with no pus formation and delayed separation of the umbilical cord.
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|AnswerE=Precipitation of monosodium urate crystals in joints on arthrocentesis
|AnswerE=Precipitation of monosodium urate crystals in joints on arthrocentesis
|AnswerEExp=Gout is caused by precipitation of monosodium urate crystals (MSU) in joints. It is a common complication of hyperuricemia.
|AnswerEExp=Gout is caused by precipitation of monosodium urate crystals (MSU) in joints. It is a common complication of hyperuricemia.
|EducationalObjectives=Adenosine deaminase deficiency is a common cause of SCID
|RightAnswer=B
|RightAnswer=B
|WBRKeyword=lymph, node, biopsy, germinal, center, centers, B cell, T cell, severe, combined, immunodeficiency, SCID, adenosine, deaminase
|WBRKeyword=lymph, node, biopsy, germinal, center, centers, B cell, T cell, severe, combined, immunodeficiency, SCID, adenosine, deaminase
|Approved=No
|Approved=No
}}
}}

Revision as of 21:11, 2 September 2014
Author [[PageAuthor::Rim Halaby, M.D. [1]]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Biochemistry
Sub Category SubCategory::General Principles
Prompt [[Prompt::A 5-year-old boy is diagnosed with a disorder characterized by the deficiency of enzyme X. The enzyme is an essential component of the pathway shown below. Which of the following is most likely to be a clinical feature of this patient's condition?

]]

Answer A AnswerA::Delayed separation of umbilical cord
Answer A Explanation AnswerAExp::Leukocyte adhesion deficiency (type I) is due to a defect in LFA-1 integrin. Patients typically present with recurrent bacterial infections with no pus formation and delayed separation of the umbilical cord.
Answer B AnswerB::Absence of germinal centers on lymph node biopsy
Answer B Explanation AnswerBExp::Absence of germinal centers on lymph node biopsy due to absence of B cells is found in SCID.
Answer C AnswerC::Thrombocytopenic purpura and eczema
Answer C Explanation AnswerCExp::Thrombocytopenic purpura, eczema, and infections are found in patients with Wiskott-Aldrich syndrome, caused by inability of T-cell reorganization of actin cytoskeleton.
Answer D AnswerD::Self-mutilation and choreoathetosis
Answer D Explanation AnswerDExp::Self-mutilation and choreoathetosis are found in patients with Lesch-Nyhan syndrome, caused by a deficiency of HGPRT.
Answer E AnswerE::Precipitation of monosodium urate crystals in joints on arthrocentesis
Answer E Explanation AnswerEExp::Gout is caused by precipitation of monosodium urate crystals (MSU) in joints. It is a common complication of hyperuricemia.
Right Answer RightAnswer::B
Explanation [[Explanation::The patient has adenosine deaminase deficiency, a common cause of severe combined immunodeficiency (SCID). The disease is an X-linked disorder characterized by B cell and T cell deficiency. Accordingly, patients present with recurrent infections, thymic aplasia, and loss of germinal centers on lymph node biopsy.

Educational Objective: Adenosine deaminase deficiency is a common cause of SCID
References: ]]

Approved Approved::No
Keyword WBRKeyword::lymph, WBRKeyword::node, WBRKeyword::biopsy, WBRKeyword::germinal, WBRKeyword::center, WBRKeyword::centers, WBRKeyword::B cell, WBRKeyword::T cell, WBRKeyword::severe, WBRKeyword::combined, WBRKeyword::immunodeficiency, WBRKeyword::SCID, WBRKeyword::adenosine, WBRKeyword::deaminase
Linked Question Linked::
Order in Linked Questions LinkedOrder::
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