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': "In a patient, muscle cramps on exercise, +ve myoglobtalinemia, the disorder is – \nSelect and explain. \nA. Pompe's disease, B. Myotonia congenita, C. Myotonic dystrophy, D. Mc ardle's disease", 'role': 'user'}, {'content': 'Answer: D \nExplanation: McArdle\'s disease \n\nThis is due to deficiency of muscle phosphorylase.\nLack of this enzyme limits muscle ATP generation by glycogenolysis results in glycogen occ\n\nClinical manifestations -\n\nDevelop in late childhood or adult\nExercise intolerance with a muscle cramp\nIt is important to note that two types of activity tend to cause symptoms;\n\ni) The brief exercise of great intensity such as sprinting\nii) Less intense but sustained activity, such as climbing stairs or walking uphill.\n\nModerate exercise, such as walking on level ground, can be performed by most patients for long periods.\nMany patients experience a characteristic "Second wind" phenomenon If they slow down briefly at the 1st appearance of muscle pain, they can resume exercise with more ease.\nThere may be exercise-induced myoglobinuria secondary to rhabdomyolysis.\nThis can lead to acute renal failure.\nSerum creatine kinase is elevated.', 'role': 'assistant'}]