We found that circulating glutamine levels were significantly elevated in both heritable PAH patients (451 ± 68 umol/L) and in BMPR2 mutation carriers (450 ± 50 umol/L) compared to controls (399 ± 82  umol/L, P < 0.05, Fig. 1a). Here, BMPR2 is linked to pulmonary arterial hypertension.