RESEARCH ARTICLE Osteogenesis Imperfecta Type V: Clinical and Radiographic Manifestations in Mutation Confirmed Patients Ok-Hwa Kim, 1 Dong-Kyu Jin, 2 Keisuke Kosaki, 3 Jung-Wook Kim, 4 Sung Yoon Cho, 2 Won Joon Yoo, 5 In Ho Choi, 5 Gen Nishimura, 6 Shiro Ikegawa, 7 and Tae-Joon Cho 5 * 1 Department of Radiology, Ajou University Medical School, Suwon, Republic of Korea 2 Department of Pediatrics, Samsung Medical Center, Sungkyunkwan University, Seoul, Republic of Korea 3 Department of Orthopedic Surgery, Faculty of Medicine, University of Tokyo, Tokyo, Japan 4 Department of Pediatric Dentistry, School of Dentistry, Seoul National University, Seoul, Republic of Korea 5 Division of Pediatric Orthopaedics, Seoul National University Children’s Hospital, Seoul, Republic of Korea 6 Department of Pediatric Imaging, Tokyo Metropolitan Children’s Medical Center, Kiyose, Japan 7 Laboratory of Bone and Joint Disease, Center for Genomic Medicine, RIKEN, Tokyo, Japan Manuscript Received: 12 November 2012; Manuscript Accepted: 11 April 2013 Osteogenesis imperfecta (OI) type V is a specific OI phenotype with interosseous membrane calcification of the forearm and hyperplastic callus formation as typical features. The causative gene mutation for OI type V has been recently discovered. The purpose of this report is to review the clinical and radiographic characteristics of mutation confirmed OI type V in detail. Sixteen (nine familial and seven sporadic) patients were enrolled in the study. Blue sclera and dentinogenesis imperfecta were not evident in any patient. However, hypodontia in the permanent teeth, ectopic eruption, and short roots in molars were additionally observed in 11 patients. Of the radiographic abnormalities, cortical thickening and bony excrescence of interosseous margin of the ulna was the most common finding, followed by overgrowth of the olecranon and/or coronoid process of the ulna. Slender ribs and sloping of the posterior ribs with or without fractures were also a consistent finding. Hyperplastic callus was detected in 75% of patients and was commonly encountered at the femur. Heterotopic ossification in the muscles and tendon insertion sites were noted in four patients, which resulted in bony ankylosis or contracture of joints. The current study confirms common clinical and radio- graphic findings of OI type V and reports additional phenotypic information. These observations provide clues to recognize OI type V more promptly and guide to direct targeted molecular study. Ó 2013 Wiley Periodicals, Inc. Key words: osteogenesis imperfecta; fractures; interosseous membrane; hyperplastic callus; heterotopic ossification INTRODUCTION Osteogenesis imperfecta (OI) is a heterogeneous group of genetic disorders characterized by fragile bones with multiple fractures and ensuing skeletal deformities. The majority of OI cases are caused by heterozygous mutation of either COL1A1 or COL1A2 encoding the a1 or a2 chains of type 1 collagen, respectively, and are inherited in an autosomal dominant pattern [Roughley et al., 2003; Rauch and Glorieux, 2004]. Some OI cases were found to be autosomal recessive, and six more genes responsible for these recessive OI have been discovered [Rohrbach and Giunta, 2012]. However, the proposed classification of OI into types I–IV [Sillence et al., 1979] remains the mainstay of the clinical classification system. Glorieux et al. [2000] proposed a new type of autosomal dominant OI similar to type IV, but with specific clinical, radiological, and/or histological features includ- ing limitations in the range of pronation/supination in forearms with How to Cite this Article: Kim O-H, Jin D-K, Kosaki K, Kim J-W, Cho SY, Yoo WJ, Choi IH, Nishimura G, Ikegawa S, Cho T-J. 2013. Osteogenesis imperfecta type V: Clinical and radiographic manifestations in mutation confirmed patients. Am J Med Genet Part A 161A:1972–1979. Conflict of interest: none.  Correspondence to: Dr. Tae-Joon Cho, M.D., Division of Pediatric Orthopaedics, Seoul National University Children’s Hospital, 101 Daehang-ro Jongno-gu, Seoul 110-744, Republic of Korea. E-mail: tjcho@snu.ac.kr Article first published online in Wiley Online Library (wileyonlinelibrary.com): 26 June 2013 DOI 10.1002/ajmg.a.36024 Ó 2013 Wiley Periodicals, Inc. 1972