No statistically significant differences were found in C3 [1.14 g/L (IQR 1.03–1.24 g/L) vs. 1.12 g/L (IQR 0.99–1.23 g/L); p > 0.05], C4 [0.2 g/L (IQR 0.16–0.25 g/L) vs. 0.2 g/L (IQR 0.16–0.23 g/L); p > 0.05], C2 [26.4 mg/L (IQR 24.7–32.5 mg/L) vs. 26.1 mg/L (23.3–32.1 mg/L); p > 0.05] and CH50 [75.19 U/mL (IQR 64.82–98.47 U/mL) vs. 79.24 U/mL (IQR 66.21–87.68 U/mL); p > 0.05] between SSc patients undergoing steroid therapy and SSc patients not treated with steroids. The gene discussed is C3; the disease is systemic sclerosis.