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': 'Leukocyte-adhesion deficiency 2 is due to the absence of __________. \nSelect and explain. \nA. Selectin, B. LFA-1, C. MAC 1, D. Sialyl-Lewis X', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Leukocyte\xa0 adhesion\xa0 deficiencies\xa0 (LADs)\xa0 stem\xa0 from\xa0 inherited defects in adhesion molecules that impair leukocyte recruitment to sites of infection, resulting in recurrent bacterial infections.\n\nLAD1 is caused by defects in the β 2\xa0 chain that is shared by the integrins LFA-1 and Mac-1.\xa0\nLAD2 is caused by a defect in a fucosyl transferase that is required to synthesize functional sialyl-Lewis X, the ligand for E- and P-selectins.\n\n\u200bReference-Robbins BASIC PATHOLOGY 10th edition pg-172', 'role': 'assistant'}]