This suggests that overexpression of BMP8A and TGF-β1 may contribute to intracellular production and accumulation of Col II and Col X. To verify this, we co-transfected si-BMP8A and pc-TGF-β1, and pc-BMP8A and pc-TGF-β1 in chicken chondrocytes of TD. The gene discussed is TGFB1; the disease is thanatophoric dysplasia.