WBR0185

Author	[[PageAuthor::Ogheneochuko Ajari, MB.BS, MS [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Genetics, MainCategory::Pathology
Sub Category	SubCategory::Oncology
Prompt	[[Prompt::A 14-year old male presented to the emergency department with severe headaches, dyspnea on exertion and petechiae on the lower extremeties. A CBC was drawn that showed a WBC count of 75, 000/uL, Hb of 8.5g/dl, hematocrit of 22. A bone marrow biopsy performed showed 70% of lymphoid blasts. The blast population expressed CD19, CD20, CD22, CD10 and TdT. The patient was subsequently diagnosed with pre-B acute lymphoblastic leukemia. Which of the following is indicated as a good prognostic marker?]]
Answer A	AnswerA::t(12;21) translocation
Answer A Explanation	AnswerAExp::t(12, 21) translocation offers a better or favorable prognosis in ALL and this aids in the selection of therapies for cases of ALL
Answer B	AnswerB::t(11;22) translocation
Answer B Explanation	AnswerBExp::t(11,22) translocation is associated with Ewing’s sarcoma
Answer C	AnswerC::Ten-eleven translocation 2 (TET2)
Answer C Explanation	AnswerCExp::Ten-eleven translocation 2 (TET2) is a gene located on chromosome 4q24. Mutations’ involving this gene is found in myeloid malignancies including myelodysplastic syndromes, CML, AML. It is not a prognostic indicator in ALL
Answer D	AnswerD::TdT
Answer D Explanation	AnswerDExp::TdT is a protein expressed early in the development of pre-T and pre-B cells but it is not a prognostic marker of the disease
Answer E	AnswerE::Isocitrate dehydrogenase 1/2 (IDH1/IDH2)
Answer E Explanation	[[AnswerEExp::Isocitrate dehydrogenase 1 (IDH1) is a gene located in chromosome 2q33.3 while IDH2 is located in chromosome 15q26.1. These genes are responsible for encoding enzymes catalyzing oxidative decarboxylation of isocitrate to alpha ketoglutarate. Mutations in this gene confer poor prognosis in certain subsets of AML]]
Right Answer	RightAnswer::A
Explanation	[[Explanation::The patient in this vignette has Acute Lymphoblastic Leukemia (ALL), which is the most common leukemia in children from newborn to 14 years of age. It is a clonal lymphoid stem cell disease. It could be of the early pre-B-cell leukemia or the T-cell ALL. T(12,21) translocation is the most common structural chromosome change on childhood cancer and is exclusively associated with the B-cell precursor subset of ALL. The translocation generates TEL-AML1 (ETV6-RUNXI) fusion gene, which is associated with a more favorable prognosis as evidenced by a significantly lower relapse rate. Evaluation of this and other prognostic markers helps in selecting low toxicity versus high toxicity therapies Educational Objective: t(12,21) translocation is a good prognostic marker in cases of ALL Educational Objective: References: ]]
Approved	Approved::Yes
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