TNF and pulmonary arterial hypertension: Similarly, an IQR increase in total PAH of 0.560 ppb was associated with 0.105 pg/mL higher TNF-alpha level among haplogroup H subjects (p = 0.032), versus a nonsignificant 0.09 pg/mL decrease (p = 0.205) among U subjects (interaction p = 0.73).