In patients with SSc, CXCL16 was significantly elevated in those with pulmonary arterial hypertension (5.7 ng/ml ± 1.2, n = 2) compared to those without (4.5 ng/ml ± 0.1, n = 18, P < 0.05, Table 1). This evidence concerns the gene CXCL16 and systemic sclerosis.