Whilst the vast majority of lethal OI is associated with AD and AR variants in the collagen I genes, approximately 5% of lethal OI cases are caused by the CRTAP, P3H1, PPIB and CREB3L1 pathogenic variants (genetic OI types VII-IX, XVI) [34, 83, 97–99]. Here, CRTAP is linked to osteogenesis imperfecta.