According to the clinical severity [21, 22], OI patients were classified as OI-type I, type III, type IV, and type V. OI-type III children had significantly lower LCN2 levels (26.23 ± 14.83 ng/mL) than children with type I (39.14 ± 23.29 ng/mL) and type IV OI (39.59 ± 23.89 ng/mL) (Fig. 1a, Table 2). The gene discussed is LCN2; the disease is osteogenesis imperfecta.