RT Book, Section A1 Bianchi, Diana W. A1 Crombleholme, Timothy M. A1 D'Alton, Mary E. A1 Malone, Fergal D. SR Print(0) ID 1106399997 T1 Osteogenesis Imperfecta T2 Fetology: Diagnosis and Management of the Fetal Patient, 2e YR 2015 FD 2015 PB McGraw-Hill Education PP New York, NY SN 978-0-07-144201-5 LK obgyn.mhmedical.com/content.aspx?aid=1106399997 RD 2024/12/11 AB Key PointsClinically and genetically heterogeneous disorder manifested by bone fragility and low bone mass.Seven distinct subtypes exist. Severity is as follows: type II > type III > types IV = V = VI = VII > type I.Most cases that present prenatally are types II or III. Only 10% of fetuses with type I have fractures in utero.Other findings include blue sclerae, abnormal teeth, joint hyperlaxity, adult-onset hearing loss, and normal intelligence.Prenatal sonographic findings include long bone fractures with callus formation, limb shortening, poor mineralization of the skull, and bent femurs.Differential diagnosis includes campomelic dysplasia, hypophosphatasia, and achondrogenesis.In 90% of cases there is a mutation in one of the genes that codes for type I procollagen, COL1A1 or COL1A2.Most cases are dominantly inherited. If parents are asymptomatic there is a 7% recurrence risk due to the surprisingly high incidence of gonadal mosaicism.