The first point that we observed, was the statistically significant increase of serum OPG levels in children with documented bacterial infections (4.17 pmol/L (2.40–12.12)) compared to the viral infection group (3.2 pmol/L (1.66–5.33)) and controls (3 pmol/L (2.13–4.76)) (p < 0.001). This evidence concerns the gene TNFRSF11B and viral infectious disease.