KDR and pulmonary arterial hypertension: Eyries et al. reported two index cases with KDR mutations after prospectively screening a series of 311 unrelated patients referred for PAH genetic investigation; the KDR mutations were associated with a particular form of PAH characterized by a low diffusing capacity for carbon monoxide adjusted for hemoglobin (D (LCO)c) and radiological evidence of parenchymal lung disease, including interstitial lung disease and emphysema [81].