A 16-Year-Old Boy with Facial Pain and Headache - Fibrous dysplasia
Fibrous dysplasia 1. Cause and Etiology Fibrous dysplasia (FD) is a non-heritable, sporadic developmental bone disorder caused by a postzygotic activating mutation in the GNAS gene . · GNAS mutation : The mutation affects the GNAS1 gene located on chromosome 20q13.3, which encodes the α-subunit of the stimulatory G-protein (Gsα). This results in constitutive activation of adenylate cyclase, leading to increased cyclic AMP (cAMP) levels. · The mutation occurs postzygotically , meaning after fertilization. Therefore, the disease is not inherited but results from a somatic mutation. · This mutation leads to abnormal osteoblastic differentiation and proliferation , replacing normal bone and marrow with fibrous tissue and immature woven bone. 2. Pathophysiology Fibrous dysplasia is characterized by the replacement of n...