COL1A1 and osteogenesis imperfecta: To understand the impact of WNT1 variants on the bone signature, we performed liquid-phase chromatography spectrometry proteomics on bone tissues isolated from controls (OI patients with splicing or frameshift variants in COL1A1: Control-1, 3 and 4) and type XV OI patients (XVOI-2, 3 and 4).