Comparative expression pattern analysis revealed the involvement of catabolic enzymes (MMP1, -2, -13, ADAM10), chemokines (IL8, CCL2, CXCL2, CXCL12, CCXL14), and genes associated with cell death (TNFSF10, PMAIPI, AHR) and skeletal development (GPNMB, FRZB) including transcription factors (WIF1, DLX5, TWIST1) and growth factors (IGFBP1, -3, TGFB1) consistent with published data from human OA cartilage.
The presence of a small degree of differential allelic expression in a low proportion (24%) of the individuals studied suggests that polymorphism in FRZB cis-acting regulatory elements can be discounted as a major factor that could influence the development of OA.
Our results confirm that the R324G variant of the FRZB gene is involved in OA and indicate a role of this variant in several generalized OA phenotypes.