Consistent with our transgenic mouse model, others subsequently published a CRISPR/Cas9-knockin mouse model that also exhibited a severe OI phenotype with perinatal lethality (20, 21), suggesting that a conditional, tissue- and stage-specific expression of the mutant Ifitm5 may be an effective approach for mechanistic analyses. Here, IFITM5 is linked to osteogenesis imperfecta.