USMLE Forum Archives - USMLE Step 1 - Pathology 43
Pathology 43
TheOne - 12-06-06 10:55
An 8-month-old boy baby is evaluated because of repeated episodes of pneumococcal pneumonia. Serum studies demonstrate very low levels of IgM, IgG, and IgA. This patient's condition is thought to be related to a deficiency of which of the following proteins?
A. Adenosine deaminase
B. Class III MHC gene
C. Gamma chain of the IL-2 receptor
D. Purine nucleotide phosphorylase
E. Tyrosine kinase
TheOne - 12-06-06 10:55
An 8-month-old boy baby is evaluated because of repeated episodes of pneumococcal pneumonia. Serum studies demonstrate very low levels of IgM, IgG, and IgA. This patient's condition is thought to be related to a deficiency of which of the following proteins?
A. Adenosine deaminase
B. Class III MHC gene
C. Gamma chain of the IL-2 receptor
D. Purine nucleotide phosphorylase
E. Tyrosine kinase
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#1
Re: Pathology 43 simple - 12-09-06 13:29 i think the answer is A mThis pt may have SCID ....Severe Combined Immunodeficiency...which can be x linked od autsomal recessive. it is linked to a stem cell defect thus causing a deficit of both stem cell and humoral mediated immunity. There is a deficit of Adenosine Deaminase so deoxyadenosine accumulates which is toxic to the lymphois tissues. Correct me if i am wrong.
#2
Re: Pathology 43 simple - 12-11-06 09:49 hi again, this question is a bit tricky i must admit. i have been thinking about it and have changed my mind.
There is no evidence of T cell involvement so my original thought of SCID most likely is incorrect. Therefore i have to go with E.. Tyrosine kinase. The patient seems to have Agammaglobulinenia of Bruton which is also x linked. It affects male infants is Xlinked and involves mutation of Btk... B cell Bruton Tyrosine Kinase. There is a deficiency in the production of B cells which leads to deficiency in plasma cells and thus gammaglobulins. Hope i'm correct this time.
#3
correct
TheOne - 12-11-06 11:13 Explanation: The correct answer is E. The patient in the question stem has X-linked (Bruton's) agammaglobulinemia, which is now thought to be due to a deficiency in a tyrosine kinase, leading to a B cell maturation arrest at the pre-B cell level. Selective IgA deficiency has been linked to defective class III MHC genes (choice B). Severe combined immunodeficiency is apparently a heterogeneous disease, and different subgroups have been linked to abnormalities of adenosine deaminase (choice A), the gamma chain of the IL-2 receptor (choice C), and purine nucleotide phosphorylase (choice D).
#4
Re: Pathology 43 galaxy - 05-28-10 02:41 An 8-month-old boy baby is evaluated because of repeated episodes of pneumococcal pneumonia. Serum studies demonstrate very low levels of IgM, IgG, and IgA. This patient's condition is thought to be related to a deficiency of which of the following proteins?
E. Tyrosine kinase
#5
Re: Pathology 43 babbu5508 - 06-21-10 15:44 E. Tyrosine kinase..this a agammaglobulinemia as serum studies demonstrate very low levels of IgM, IgG, and IgA............
#6
Re: Pathology 43 bingousmle - 06-30-10 21:46 E.. Tyrosine kinase. The patient seems to have Agammaglobulinenia of Bruton which is also x linked. It affects male infants is Xlinked and involves mutation of Btk
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