The mean intensity of SMA (60.9 ± 3.1 versus 35.8 ± 6.6, p = 0.0056) and CXCL12 (26.4 ± 1.9 versus 15.3 ± 2.7, p = 0.0028) were both increased in the vasculature of patients with PAH–CHD compared to nondiseased controls (Fig. 6, B + C). This evidence concerns the gene SMN1 and pulmonary arterial hypertension.