GDF6 and coloboma: Pleiotropic defects have been described as a result of Gdf6 knockout, knockdown, or variation in mice, zebrafish, or Xenopus laevis including defects in joint, ligament, and cartilage formation causing carpal and tarsal fusions and coronal craniosynostosis [42], altered tail tendon fascicles [43], shorter lengths of digits and dermal flat bones in the skull [44], microphthalmia, anophthalmia, and coloboma [20, 45].