This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Infectious Lung Disease: Pneumonia, Subject name: Pathology
Which of the following genes is associated with familial pulmonary aerial hypeension? 
Select and explain. 
A. BMPR2, B. VEGF, C. a1-antitrypsin, D. CFTR
A: BMPR2
Answer: A: BMPR2 
Explanation: The first mutation to be discovered in familial pulmonary aerial hypeension was in the gene encoding bone morphogenetic protein receptor type 2 (BMPR2). Inactivating germline mutations in the BMPR2 gene are found in 75% of the familial cases of pulmonary hypeension and 25% of sporadic cases. BMPR2 is a cell surface protein belonging to the TGF-b receptor superfamily, which binds a variety of cytokines, including TGF-b, bone morphogenetic protein (BMP), activin, and inhibin. Haploinsufficiency for BMPR2 leads to dysfunction and proliferation of endothelial cells and vascular smooth muscle cells.