This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
[{'content': 'In primary pulmonary hypeension, basic abnormality in gene lies in \nSelect and explain. \nA. Bone morphogenic protein receptor II, B. Endothelin, C. Homebox gene, D. PAX - 11', 'role': 'user'}, {'content': "Answer: A \nExplanation: Decreased expression of the voltage-regulated potassium channel, mutations in the bone morphogenetic protein-2 receptor, increased tissue factor expression, overactivation of the serotonin transpoer, transcription factor activation of hypoxia-inducible factor-1 alpha, and activation of nuclear factor of activated T cells. As a result, there appears to be a loss of apoptosis of the smooth muscle cells that allow their proliferation and the emergence of apoptosis-resistant endothelial cells that can obliterate the vascular lumen.Ref: Harrison's 18/e p2077", 'role': 'assistant'}]