Compared with healthy control subjects, SSc patients had higher circulating levels of TNFα (P < 0.0001), IL-6 (P < 0.0001) and IL-13 (P = 0.05) but lower circulating levels of IL-17 (P = 0.0009) and IL-23 (P = 0.04). This evidence concerns the gene IL6 and systemic sclerosis.