In primary pulmonary hypeension, basic abnormality in gene lies in

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