NOTCH3 and pulmonary arterial hypertension: In addition, elevations of serum NOTCH3-ECD were not observed in individuals with other WHO group 1 subgroups, including heritable PAH (Fig. 3b), other vasculitides including cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) (Fig. 3c), or malignancies known to express NOTCH3 (Fig. 3d).