The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Down syndrome is caused by all except:   (A) Trisomy of 21 chromosome   (B) Mosaicism of 21 chromosome   (C) Robertsonian translocation of 21.21, 21.18   (D) Deletion of 21
['(D) Deletion of 21 <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Trisomy of 21 chromosome \n (B) Mosaicism of 21 chromosome \n (C) Robertsonian translocation of 21.21, 21.18 \n (D) Deletion of 21 <> possible answers', '  Down syndrome is caused by all except: <> context@']