Finally, this heterogeneity in phenotype might be a common feature of connective tissue disorders since it is also observed in osteogenesis imperfecta (OI) and selected mutations in col1a1 and col1a2 paralogs in the zebrafish model give rise to phenotypic variability, mirroring the clinical variability associated with human disease pathology [40]. This evidence concerns the gene COL1A1 and osteogenesis imperfecta.