Osteoporosis-pseudoglioma syndrome

Osteoporosis-pseudoglioma syndrome (OPPG), also known as osteogenesis imperfecta–ocular form or blind-bone disease, is a rare genetic disorder characterized by the combination of severe early-onset osteoporosis and eye abnormalities that resemble retinal tumors (pseudoglioma) but are actually caused by abnormal development of the vitreous and retina. The condition is caused by loss-of-function mutations in the LRP5 gene (low-density lipoprotein receptor-related protein 5), which plays a critical role in the Wnt signaling pathway essential for both bone formation and eye development. The skeletal manifestations typically become apparent in early childhood and include severely reduced bone mineral density, recurrent fractures from minimal trauma, progressive skeletal deformities (including kyphosis and limb bowing), and short stature. Fractures may begin in infancy or early childhood and can lead to significant disability. The ocular features are usually present at birth or develop in early infancy, consisting of vitreoretinal dysplasia, retinal detachment, and persistent hyperplastic primary vitreous, which often lead to blindness or severe visual impairment. The retrolental masses seen on examination can be mistaken for retinoblastoma, hence the term pseudoglioma. Some patients may also exhibit mild intellectual disability, muscular hypotonia, and ligamentous laxity. Treatment is primarily supportive and aimed at managing symptoms. Bisphosphonate therapy (such as intravenous pamidronate) has been shown to improve bone mineral density and reduce fracture rates in affected individuals, though it does not fully normalize bone strength. Orthopedic interventions including intramedullary rodding may be necessary for fracture management and correction of skeletal deformities. Unfortunately, the ocular abnormalities are generally not amenable to treatment, and visual loss is usually permanent, though early vitreoretinal surgery has been attempted in some cases with limited success. Genetic counseling is recommended for affected families.

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