COL3A1 and Bloom syndrome: As shown in Fig. 1, compared with saline treated mice, BLM induced marked hypodermal thickness (Fig. 3A and 3B), increase of ECM deposition and collagen contents (Fig. 3C and 3D), enhancement of the transcription levels of Col1a2 and Col3a1. Furthermore, HSP47 expression level was examined in this mouse model.