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Popcorn calcification in osteogenesis imperfecta: Incidence, progression, and molecular correlation

Authors

  • Abimbola A. Obafemi,

    1. Bone and Extracellular Matrix Branch, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, Maryland
    2. UMDNJ, New Jersey Medical School, Newark, New Jersey
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  • Dorothy I. Bulas,

    1. Department of Diagnostic Imaging and Radiology, Children's National Medical Center, Washington, District of Columbia
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  • James Troendle,

    1. Biometry and Mathematical Statistics Branch/DESPR, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, Maryland
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  • Joan C. Marini

    Corresponding author
    1. Bone and Extracellular Matrix Branch, The Eunice Kennedy Shriver National Institute of Child Health and Human Development, NIH, Bethesda, Maryland
    • Chief, Bone and Extracellular Matrix Branch, National Institute of Child Health and Human Development, NIH, Bldg 10; Rm 10N260, 9000 Rockville Pike, Bethesda, MD 20892.
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  • This article is a US Government work and, as such, is in the public domain in the United States of America.

  • How to cite this article: Obafemi AA, Bulas DI, Troendle J, Marini JC. 2008. Popcorn calcification in osteogenesis imperfecta: Incidence, progression, and molecular correlation. Am J Med Genet Part A.

Abstract

Osteogenesis imperfecta (OI) is a heritable disorder characterized by osteoporosis and increased susceptibility to fracture. All children with severe OI have extreme short stature and some have “popcorn” calcifications, areas of disorganized hyperdense lines in the metaphysis and epiphysis around the growth plate on lower limb radiographs. Popcorn calcifications were noted on radiographs of two children with non-lethal type VIII OI, a recessive form caused by P3H1 deficiency. To determine the incidence, progression, and molecular correlations of popcorn calcifications, we retrospectively examined serial lower limb radiographs of 45 children with type III or IV OI and known dominant mutations in type I collagen. Popcorn calcifications were present in 13 of 25 type III (52%), but only 2 of 20 type IV (10%), OI children. The mean age of onset was 7.0 years, with a range of 4–14 years. All children with popcorn calcifications had this finding in their distal femora, and most also had calcifications in proximal tibiae. While unilateral popcorn calcification contributes to femoral growth deficiency and leg length discrepancy, severe linear growth deficiency, and metaphyseal flare do not differ significantly between type III OI patients with and without popcorn calcifications. The type I collagen mutations associated with popcorn calcifications occur equally in both COL1A1 and COL1A2, and have no preferential location along the chains. These data demonstrate that popcorn calcifications are a frequent feature of severe OI, but do not distinguish cases with defects in collagen structure (primarily dominant type III OI) or modification (recessive type VIII OI). © 2008 Wiley-Liss, Inc.

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