SERPINH1 and osteogenesis imperfecta: On the other hand, knocking out HSP47 expression in mouse embryos results in abnormally oriented epithelial tissues and ruptured blood vessels due to severe deficiency in mature forms of type I and type IV collagen leading to a lethal phenotype (55), while in humans homozygosity for a missense mutation causes a recessive moderate to severe form of OI with distinct effects on collagen I secretion and structure depending on the type of defect (56).