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: Pediatrics
[{'content': 'Duchenne Muscular Dystrophy is a disease of – \nSelect and explain. \nA. Neuromuscular junction, B. Sarcolemmal proteins, C. Muscle contractile proteins, D. Disuse atrophy due to muscle weakness', 'role': 'user'}, {'content': "Answer: B \nExplanation: DUCHENNE MUSCULAR DYSTROPHY (PSEUDO HYPERTROPHIC MUSCULAR DYSTROPHY)\n\nDuchenne muscular dystrophy is the most common hereditary neuromuscular disease affecting all races and ethnic groups.\nInheritance: X linked recessive\nPresentation occurs between ages 3 and 5 \n\n\nPathogenesis\n\nDuchenne muscular dystrophy is caused by a mutation in the gene responsible for producing dystrophin.\nDystrophin is `subsarcolemmal protein' localized to the inner surface of the sarcolemma of the muscle fibre.\nDystrophin is part of Dystrophin - Glycoprotein sarcolenzmal complex and this protein deficiency leads to secondary loss of sarcoglycans and dystroglycans resulting in weakness of sarcolemma, causing membrane tears and muscle fibre necrosis.\n\nClinical manifestations:\n\nGower's sign is positive\nPseudohypertrophy of the calf is seen (muscle is replaced by fat & connective tissue)\nLoss of muscle strength is progressive.\nProximal muscles and neck flexors are involved more\nLeg involvement is more severe than arm involvement.\nContractures of heel cords and iliotibial band occurs (by age of 6 years)\nprogressive scoliosis develops.\n\nComplications:\n\nChest deformity (scoliosis): Impairs pulmonary function By age of 16 and 18 years patients are predisposed to serious pulmonary fatal infections.\nCardiac:\xa0Cardiomyopathy and CHF may be seen Cardiac cause of death is uncommon\nIntellectual impairment: is common (IQ is one SD below the mean)", 'role': 'assistant'}]