The serum DKK1 concentration was 5.20 (4.61, 6.19) ng/mL, 5.67 (4.29, 6.42) ng/mL and 4.80 (4.06, 6.48) ng/mL in children with type I, type III OI and type IV OI, respectively (Table 2). Here, DKK1 is linked to osteogenesis imperfecta.