<prompt> In primary pulmonary hypeension basic abnormality in gene lies in:Bone morphogenetic protein receptor IIEndothelinHomebox genePAX - 11  <response>: Answer is A Bone morphogenic Receptor Protein II Gene coding the type II bone morhphogenetic protein receptor II BMPR II is associated with familial cases of primary pulmonary hypeension and designated as the PPH I gene. Bone morphogenic protein receptor II BMPRII and pulmonary Hypeension BMPRII is a cell surface protein receptor belonging to the TGF-13 receptor superfamily located on chromosome 2q31 BMP-BMPRII signaling plays an impoant role in embryogenesis, apoptosis, cell proliferation and differentiation. In vascular smooth muscles normal BMPR2 signalling causes inhibition of proliferation and our apoptosis, thereby protecting the vessels from narrowing and development of hypeension Primary pulmonary hypeension is believed to be caused by a mutation in the gene coding for the BMPR II signaling pathway PPH-1 geneBMPRII gene Mutation in the BMPR II gene PPH-Igene predisposes the cells to undergo proliferation rather than apoptosis and results in development of pulmonary hypeension. 