This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Acute Lymphoblastic Leukemia, Subject name: Pathology
[{'content': 'All of the following are good prognostic factors for pediatric acute lymphoblastic leukemia, except: \nSelect and explain. \nA. CNS disease at diagnosis, B. Initial WBC count of 50000/cumm, C. Hyperdiploidy, D. t(12;21)', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Favorable prognostic markers include Age between 1 and 10 years, A low white cell count at diagnosis, Hyperdiploidy, Trisomy of chromosomes 4, 7, and 10, and the presence of a t(12;21). Several factors are associated with a worse prognosis: Infancy, older age at diagnosis (presentation in adolescence or adulthood) Translocations involving the MLL gene Higher WBC count at diagnosis (peripheral blood blast counts greater than 100,000/cumm) Presence of CNS disease at diagnosis Hypodiploidy', 'role': 'assistant'}]