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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor=Gerald Chi
|QuestionAuthor=Gerald Chi (Reviewed by  {{YD}})
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Biochemistry, Pathology
|MainCategory=Biochemistry, Pathophysiology
|SubCategory=Musculoskeletal/Rheumatology
|SubCategory=Musculoskeletal/Rheumatology
|MainCategory=Biochemistry, Pathology
|MainCategory=Biochemistry, Pathophysiology
|SubCategory=Musculoskeletal/Rheumatology
|SubCategory=Musculoskeletal/Rheumatology
|MainCategory=Biochemistry, Pathology
|MainCategory=Biochemistry, Pathophysiology
|SubCategory=Musculoskeletal/Rheumatology
|SubCategory=Musculoskeletal/Rheumatology
|MainCategory=Biochemistry, Pathology
|MainCategory=Biochemistry, Pathophysiology
|MainCategory=Biochemistry, Pathology
|MainCategory=Biochemistry, Pathophysiology
|MainCategory=Biochemistry, Pathophysiology
|SubCategory=Musculoskeletal/Rheumatology
|SubCategory=Musculoskeletal/Rheumatology
|MainCategory=Biochemistry, Pathology
|MainCategory=Biochemistry, Pathophysiology
|SubCategory=Musculoskeletal/Rheumatology
|SubCategory=Musculoskeletal/Rheumatology
|MainCategory=Biochemistry, Pathology
|MainCategory=Biochemistry, Pathophysiology
|SubCategory=Musculoskeletal/Rheumatology
|SubCategory=Musculoskeletal/Rheumatology
|MainCategory=Biochemistry, Pathology
|MainCategory=Biochemistry, Pathophysiology
|SubCategory=Musculoskeletal/Rheumatology
|SubCategory=Musculoskeletal/Rheumatology
|MainCategory=Biochemistry, Pathology
|MainCategory=Biochemistry, Pathophysiology
|MainCategory=Biochemistry, Pathology
|MainCategory=Biochemistry, Pathophysiology
|SubCategory=Musculoskeletal/Rheumatology
|SubCategory=Musculoskeletal/Rheumatology
|Prompt=A 30-year-old female presents with mild fever, malaise, and swollen hand and knee joints. Physical examination shows malar rash. Laboratory findings include lymphopenia with mild anemia and thrombocytopenia. A diagnosis is made by the presence of homogeneous pattern of anti-nuclear antibody as well as of a certain type of autoantibodies against the RNA. Which of the following types of RNA is most likely to be the target?
|Prompt=A 30-year-old woman presents with mild fever, malaise, and swollen hand and knee joints. Physical examination is remarkable for malar rash. Laboratory findings include lymphopenia with mild anemia and thrombocytopenia. A diagnosis is then made following the detection of a homogeneous pattern of anti-nuclear antibody as well as autoantibodies against RNA. Which of the following types of RNA is most likely to be the target of the antibodies?
 
|Explanation=Antinuclear antibody (ANA) is a non-specific screening test to evaluate for the presence of rheumatic diseases. ANA screening often yields positive results in many connective tissue disorders and other autoimmune diseases, and may also be positive among normal individuals. Subtypes of antinuclear antibodies include anti-Smith (targets RNA) and anti-double stranded DNA (targets dsDNA) antibodies, both of which are associated with the diagnosis of systemic lupus erythematosus (SLE), and anti-histone antibodies (targets histones), which are associated with the diagnosis of drug-induced lupus.
|Explanation=ANA screening yields positive results in many connective tissue disorders and other autoimmune diseases, and may occur in normal individuals. Subtypes of antinuclear antibodies include anti-Smith and anti-double stranded DNA (dsDNA) antibodies (which are linked to SLE) and anti-histone antibodies (which are linked to drug-induced lupus).
|AnswerA=Messenger RNA (mRNA)
|AnswerA=Messenger RNA (mRNA)
|AnswerAExp=Anti-Sm antibody does not target mRNA.


|AnswerAExp='''Incorrect'''<BR>Anti-Sm antibody does not target mRNA.
|AnswerB=Transfer RNA (tRNA)
|AnswerB=Transfer RNA (tRNA)  
|AnswerBExp=Anti-Sm antibody does not target tRNA.
 
|AnswerBExp='''Incorrect'''<BR>Anti-Sm antibody does not target tRNA.
|AnswerC=Ribosomal RNA (rRNA)
|AnswerC=Ribosomal RNA (rRNA)
|AnswerCExp='''Incorrect'''<BR>Anti-Sm antibody does not target rRNA.
|AnswerCExp=Anti-Sm antibody does not target rRNA.
|AnswerD=Small nuclear ribonucleic acid (snRNA)
|AnswerD=Small nuclear ribonucleic acid (snRNA)
 
|AnswerDExp=Anti-Sm antibody is specific for SLE. Smith antigen is a group of proteins (B/D/E/F/G) without snRNA; it is metabolized by trypsin but not by RNase.
|AnswerDExp='''Correct'''<BR>Anti-Sm antibody is highly specific for SLE. Smith antigen is a group of proteins (B/D/E/F/G) without snRNA; it is destroyed by trypsin but not by RNase.
|AnswerE=Heterogeneous nuclear RNA (hnRNA)
|AnswerE=Heterogeneous nuclear RNA (hnRNA)
 
|AnswerEExp=Anti-Sm antibody does not target hnRNA.
|AnswerEExp='''Incorrect'''<BR>Anti-Sm antibody does not target hnRNA.
|EducationalObjectives=Subtypes of antinuclear antibodies include anti-Smith (targets RNA) and anti-double stranded DNA (targets dsDNA) antibodies, both of which are associated with the diagnosis of systemic lupus erythematosus (SLE), and anti-histone antibodies (targets histones), which are associated with the diagnosis of drug-induced lupus.
|References=Migliorini P, Baldini C, Rocchi V, et al. Anti-Sm and anti-RNP antibodies. Autoimmunity. 2005;38(1):47-54.<br>
First Aid 2015 page 213, 433.
|RightAnswer=D
|RightAnswer=D
|Approved=No
|WBRKeyword=Small nuclear ribonucleic acid, snRNA, Antinuclear antibody, SLE, Systemic lupus erythematosus
|Approved=Yes
}}
}}

Latest revision as of 02:54, 28 October 2020

 
Author [[PageAuthor::Gerald Chi (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Biochemistry, MainCategory::Pathophysiology
Sub Category SubCategory::Musculoskeletal/Rheumatology
Prompt [[Prompt::A 30-year-old woman presents with mild fever, malaise, and swollen hand and knee joints. Physical examination is remarkable for malar rash. Laboratory findings include lymphopenia with mild anemia and thrombocytopenia. A diagnosis is then made following the detection of a homogeneous pattern of anti-nuclear antibody as well as autoantibodies against RNA. Which of the following types of RNA is most likely to be the target of the antibodies?]]
Answer A AnswerA::Messenger RNA (mRNA)
Answer A Explanation AnswerAExp::Anti-Sm antibody does not target mRNA.
Answer B AnswerB::Transfer RNA (tRNA)
Answer B Explanation AnswerBExp::Anti-Sm antibody does not target tRNA.
Answer C AnswerC::Ribosomal RNA (rRNA)
Answer C Explanation AnswerCExp::Anti-Sm antibody does not target rRNA.
Answer D AnswerD::Small nuclear ribonucleic acid (snRNA)
Answer D Explanation AnswerDExp::Anti-Sm antibody is specific for SLE. Smith antigen is a group of proteins (B/D/E/F/G) without snRNA; it is metabolized by trypsin but not by RNase.
Answer E AnswerE::Heterogeneous nuclear RNA (hnRNA)
Answer E Explanation AnswerEExp::Anti-Sm antibody does not target hnRNA.
Right Answer RightAnswer::D
Explanation [[Explanation::Antinuclear antibody (ANA) is a non-specific screening test to evaluate for the presence of rheumatic diseases. ANA screening often yields positive results in many connective tissue disorders and other autoimmune diseases, and may also be positive among normal individuals. Subtypes of antinuclear antibodies include anti-Smith (targets RNA) and anti-double stranded DNA (targets dsDNA) antibodies, both of which are associated with the diagnosis of systemic lupus erythematosus (SLE), and anti-histone antibodies (targets histones), which are associated with the diagnosis of drug-induced lupus.

Educational Objective: Subtypes of antinuclear antibodies include anti-Smith (targets RNA) and anti-double stranded DNA (targets dsDNA) antibodies, both of which are associated with the diagnosis of systemic lupus erythematosus (SLE), and anti-histone antibodies (targets histones), which are associated with the diagnosis of drug-induced lupus.
References: Migliorini P, Baldini C, Rocchi V, et al. Anti-Sm and anti-RNP antibodies. Autoimmunity. 2005;38(1):47-54.
First Aid 2015 page 213, 433.]]

Approved Approved::Yes
Keyword WBRKeyword::Small nuclear ribonucleic acid, WBRKeyword::snRNA, WBRKeyword::Antinuclear antibody, WBRKeyword::SLE, WBRKeyword::Systemic lupus erythematosus
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