One caused a substitution of glycine 200 by valine at the N-terminus of D1 in OI type I/IV, lowering collagen stability by 50% at 34 degrees C. The other one was a substitution of valine 349 by phenylalanine at the C-terminus of D1 in OI type I, lowering collagen stability at 37.5 degrees C. Two other mutations, reported before, changed amino residues in D4.
Consortium for osteogenesis imperfecta mutations in the helical domain of type I collagen: regions rich in lethal mutations align with collagen binding sites for integrins and proteoglycans.