WBR0185
| Author | [[PageAuthor::Ogheneochuko Ajari, MB.BS, MS [1], Serge Korjian M.D. (Reviewed by Serge Korjian)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Genetics, MainCategory::Pathology |
| Sub Category | SubCategory::Oncology |
| Prompt | [[Prompt::An 7-year-old boy is brought by his parents to the emergency department for severe left leg pain that started 2 days prior to presentation. His mother reports that the child has been very tired for the past few weeks. She also explains that her son has lost a lot of weight, and has been running out of breath with minimal activity recently. Upon further questioning, the child denies any trauma to his leg. On physical exam, you notice an ill appearing child with abdominal swelling and petechiae on the upper and lower extremities. A CBC is drawn and shows a hemoglobin of 8.5 g/dL, hematocrit of 25, and a WBC count of 75,000/uL. Which of the following findings is considered a good prognostic marker in this patient?]] |
| Answer A | AnswerA::t(12;21) translocation |
| Answer A Explanation | AnswerAExp::t(12;21) translocation is associated with a favorable prognosis and a lower relapse rate in patients with ALL. |
| Answer B | AnswerB::t(11;22) translocation |
| Answer B Explanation | AnswerBExp::t(11;22) translocation is not common among patients with ALL. It is classically associated with Ewing’s sarcoma. |
| Answer C | AnswerC::Ten-eleven translocation 2 (TET2) mutation |
| Answer C Explanation | AnswerCExp::Ten-eleven translocation 2 (TET2) is a gene located on chromosome 4q24. Mutations involving this gene are found in myeloid malignancies including myelodysplastic syndromes, CML, AML. It is not a prognostic indicator in ALL. |
| Answer D | AnswerD::Terminal deoxynucleotidyl transferase (TdT) positivity |
| 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) mutation |
| 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::Acute lymphoblastic leukemia (ALL) is the most common childhood malignancy, accounting for approximately 30% of all cancers in patients younger than 14 years of age. It is a clonal lymphoid stem cell disease. The classical presentation of patients with ALL includes fatigue, recurrent infections, bony pain, weight loss, easy bruisability, petechiae, dyspnea on exertion, and hepatosplenomegaly. t(12;21) translocation is the most common chromosomal anomaly in childhood leukemias and is exclusively found in patients with Pre-B-ALL (approximately 25% of these patients). The translocation generates TEL-AML1 (ETV6-RUNX1) 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: The t(12;21) translocation is a good prognostic marker in cases of acute lymphoblastic leukemia. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::ALL, WBRKeyword::Lymphoblast, WBRKeyword::Blasts, WBRKeyword::TdT, WBRKeyword::t(12;21), WBRKeyword::Acute Lymphocytic Leukemia, WBRKeyword::Translocations, WBRKeyword::Prognosis, WBRKeyword::Genetic anomalies, WBRKeyword::Pediatric cancers |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |