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Date: 19-12-2021
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Osteogenesis Imperfecta
This syndrome, known as “brittle bone disease,” is a genetic disorder of bone fragility characterized by bones that fracture easily, with minor or no trauma (Fig. 2). Over 80% of cases of osteogenesis imperfecta (OI) are caused by dominant mutations to the genes that encode the α1 or α2 chains in type I collagen. The most common mutations cause the replacement of glycine (in –Gly–X–Y–) by amino acids with bulky side chains. The resultant structurally abnormal α chains prevent the formation of the required triple-helical conformation.
Phenotypic severity ranges from mild to lethal. Type I OI, the most common form, is characterized by mild bone fragility, hearing loss, and blue sclerae. Type II, the most severe form, is typically lethal in the perinatal period as a result of pulmonary complications. In utero fractures are seen ( Fig. 1). Type III is also a severe form and is characterized by multiple fractures at birth, short stature, spinal curvature leading to a humped-back (kyphotic) appearance, and blue sclerae. Dentinogenesis imperfecta, a disorder of tooth development, may be seen in OI.
Figure 1: Lethal form (type II) of osteogenesis imperfecta in which the fractures appear in utero, as revealed by this radiograph of a stillborn fetus.
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في اليوم العالمي للصحة النفسية.. نصائح لتحسين مزاجك اليومي
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آلاف الأشخاص يحاولون الهروب من فلوريدا بسبب إعصار ميلتون
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لليوم الثاني.. العتبة العباسية تواصل إقامة مجلسها العزائي بذكرى شهادة السيدة فاطمة الزهراء (عليها السلام)
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