This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
[{'content': "Chromosomal non - disjunction responsible for all except? \nSelect and explain. \nA. Down's syndrome, B. Neurofibromatsis type 1, C. Pradderwilli syndrome, D. Angleman syndrome", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Neurofibromatosis type 1Nondisjunction Nondisjunction is the failure of homologous chromosomes or sister chromatids to separate properly during cell division.There are threeforms of nondisjunction: Failure of a pair of homologous chromosomes to separate in meiosisFailure of sister chromatids to separate during meiosis II, andFailure of sister chromatids to separate during mitosis.", 'role': 'assistant'}]