COL1A1 and osteogenesis imperfecta type 1: QPCR analysis demonstrated a significant reduction in COL1A1 (P < 0.01) and COL1A2 (P < 0.05) in fibroblasts from Type 1 OI patients compared with healthy controls, providing confidence that our OI cells were reflecting gene expression profiles anticipated in OI (Fig. 1A).