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  #1  
Old 06-11-2011
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DNA Which mutation responsible for these clinical features!

In the first weeks after birth, a male infant presented with generalized red rashes, diarrhea and failure to thrive. Physical examination revealed lymphadenopathy and hepatosplenomegaly. Blood culture showed S aureus and gram-negative enteric bacterial sepsis. IgE serum levels were robustly increased and levels of B- and T-cells were markedly decreased. Mutation in which of the following gene could be responsible for this condition?


A) Missense mutation in ATP7A
B) Missense mutation in RAG
C) Microdeletion of 22q11
D) Null mutation in SMPD1
E) Missense mutation in IDUA
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  #2  
Old 06-11-2011
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This sounds like Wiskott Aldrich to me but I don't see the WASP gene as an answer choice so my next guess would be SCID.

So I'll go with B) mutation in RAG
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Old 06-11-2011
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will go with B but not sure bcoz of the physical examination results !!
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Old 06-12-2011
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Post Omenn Syndrome!

B is correct. This is a typical case of Omenn Syndrome:

- Autosomal recessive severe combined immunodeficiency
- Missense mutation in recombination activating genes (rag)
- Patients have some T cells with limited levels of recombination with the mutant RAG genes. These T cells are abnormal and have a very specific affinity for self antigens found in the thymus and in the periphery. Therefore, these T cells are auto-reactive and cause the GVHD phenotype.
- Lack of B-cells
- Early FTT, chronic diarrhea, generalized red rash, severe immune deficiency
- Elevated serum IgE

It is noteworthy that in SCID we have null (not missense) mutation in RAG. Thus, there is total lack of B and T cells in SCID.
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Old 06-12-2011
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I do not think we can make definitive diagnosis based on the scenarios given in the question, the choice of B is selected by excluding other possibilities.
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Old 06-12-2011
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guys where are you guys studying these exact mutations for genetic disorders? any good source? anything?....haha, truly anything would be helpful
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Old 06-12-2011
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Quote:
Originally Posted by Dr_Kal_El View Post
guys where are you guys studying these exact mutations for genetic disorders? any good source? anything?....haha, truly anything would be helpful
The different mutations about Omenn syndrome and SCID are discussed in a table I-2-5, page 16, Kaplan Immunology lecture notes.
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Genetics-, Immunology-, Step-1-Questions, Syndromes-Acronyms

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