Anti-U1-RNP antibodies through the upregulation of the intracellular adhesion molecule-1, endothelial leukocyte adhesion molecule-1, and major histocompatibility complex (MHC) class II molecules expression may lead to the hyperplasia, obliterated vasculopathy, and pulmonary arterial hypertension (PAH). The gene discussed is SNRNP70; the disease is pulmonary arterial hypertension.