As shown in Table 2, the circulating IGFBP2 concentration was significantly increased in PAH in aggregate compared with healthy control subjects (median 350.9 ng/ml vs 170.2 ng/ml, p < 0.0001) or in the PAH subtypes IPAH (median 358.4 ng/ml, p < 0.0001) and APAH (median 344.2 ng/ml, p < 0.0001) versus healthy control (Fig. 1a), although no significant differences were observed for IGF1 (median 67.0 vs 64.7 ng/ml, p = 0.15) or IGF2 (347.8 vs 340.9 ng/ml, p = 0.56) versus PAH in aggregate. This evidence concerns the gene IGF1 and idiopathic pulmonary arterial hypertension.