title: Bulbous epiphysis and popcorn calcification as related to growth plate differentiation in osteogenesis imperfecta.
abstract: BACKGROUND
  Osteogenesis Imperfecta (OI) is an heritable systemic disorder of connective tissue due to different sequence variants in genes affecting both the synthesis of type I collagen and osteoblast function. Dominant and recessive inheritance is recognized. Approximately 90% of the OI cases are due to mutations in COL1A1/A2 genes. We clinically and radiologically describes an adult male with type III osteogenesis imperfecta who presents a rare bone dysplasia termed bulbous epiphyseal deformity in association with popcorn calcifications. Popcorn calcifications may occur with bulbous epiphyseal deformity or independently.
  
  
  METHODS
  Molecular analysis was performed for COL1A1, COL1A2, LEPRE1 and WNT1 genes.
  
  
  RESULTS
  An uncommon COL1A1 mutation was identified. Clinical and radiological exams confirmed a distinctive bulbous epiphyseal deformity with popcorn calcifications in distal femurs. We have identified four additional OI patients reported in current literature, whose X-rays show bulbous epiphyseal deformity related to mutations in CR-TAP, LEPRE1 and WNT1 genes.
  
  
  CONCLUSIONS
  The mutation identified here had been previously described twice in OI patients and no previous correlation with bulbous epiphyseal deformity was described. The occurrence of this bone dysplasia focuses attention on alterations in normal growth plate differentiation and the subsequent effect on endochondral bone formation in OI.
authors.affiliation: Bone and Osteogenesis Imperfecta Department, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA ; Postgraduate Program in Child and Adolescent Health, Faculty of Medicine, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Evelise
authors.initials: E
authors.lastname: Brizola
authors.affiliation: Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Edward
authors.initials: E
authors.lastname: McCarthy
authors.affiliation: Bone and Osteogenesis Imperfecta Department, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
authors.forename: Jay Robert
authors.initials: JR
authors.lastname: Shapiro
keywords: chondrocyte; endochondral bone formation; growth plate; osteogenesis imperfecta