Phenotype variability in a daughter and father with mild osteogenesis imperfecta correlated with collagen and prolidase levels in cultured skin fibroblasts.

Studies of collagen biosynthesis and prolidase activity were performed on cultured skin fibroblasts obtained from a female patient and her father, who displayed variable phenotypes of mild osteogenesis imperfecta (OI). For comparison, the same studies were also performed on age-matched controls. Biosynthesis of collagen in fibroblasts of the less affected father was reduced to approximately 50% of control levels, whereas in cells of the more severely affected daughter, it was decreased to about 20% of control levels. Furthermore, the decrease in collagen synthesis in OI fibroblasts was accompanied by a parallel decrease in prolidase activity and expression of beta1 integrin and insulin-like growth factor-I (IGF-I) receptors recovered from the cells. Therefore, prolidase, as well as IGF-I and beta1 integrin receptors involved in collagen metabolism regulation, may represent important factors influencing OI phenotype.