GDF6 (growth differentiation factor 6) is a member of the bone morphogenetic protein (BMP) family that serves dual functions through distinct molecular domains. The mature BMP domain regulates skeletal development and joint formation by activating SMAD1/5/8 signaling pathways, with enhanced GDF6 activity causing joint fusion disorders like multiple synostoses syndrome 1. The prodomain functions independently as a ligand for CD99, regulating Src kinase activity and cellular proliferation in contexts such as Ewing sarcoma 2. In eye development, GDF6 is essential for controlling retinal size through regulation of apoptosis, with mutations causing microphthalmia in both zebrafish models and human patients 3. GDF6 also promotes angiogenesis and wound healing, with its expression being regulated by miRNA-155-5p from M1-polarized macrophages 4. In cancer, GDF6 exhibits context-dependent roles, functioning as both a tumor suppressor and oncogene across different malignancies through activation of PI3K-Akt/VEGF pathways 5. Additionally, GDF6 contributes to intervertebral disc maintenance by promoting extracellular matrix stability 6 and plays a role in innate immune responses through FTO-mediated m6A modifications 7. The evolutionary significance of GDF6 is highlighted by its regulation through the primate-specific TOSPEAK gene, which controls laryngeal and wrist development 8.