To clarify the role(s) for LH3 in collagen biosynthesis, we generated LH3 KO cells using CRIPSR-mediated gene editing to conduct detailed quantitative and molecular analyses of collagens α1α1α2(I), α1α1α1(III), and α1α1α2(IV) implicated in OI, EDS, and Gould syndrome, respectively. The gene discussed is PLOD3; the disease is osteogenesis imperfecta.