Fibrous dysplasia/McCune-Albright syndrome (FD/MAS) is a rare and debilitating disease that has no FDA-approved treatment. FD/MAS is caused by a postzygotic mutation of the gene GNAS and leads to mosaic Gα s activation and inappropriate production of intracellular cAMP. It causes abnormal fibrous tissue to grow in place of healthy bone and often causes chronic pain, loss of mobility, hormonal imbalances, skin marks, deformity, fractures and more. FD/MAS can affect a single bone or virtually every bone in the body, resulting in facial disfigurement and ambulation difficulties requiring repeated surgeries and the use of assisted devices and wheel chairs. There is no cure and no way to slow the disease down.
FD may occur by itself in the bones or in combination with skin and endocrine (hormonal) disease. Patients may have areas of increased skin pigmentation called café-au-lait spots. These birthmarks have irregular borders, and may reflect along the midline of the body. Endocrine problems can include precocious puberty, hyperthyroidism, growth hormone excess, phosphate wasting, and Cushing’s syndrome. Patients can have one or many features of the disease, and these features can occur in any combination. The combination of two or more disease features is called McCune-Albright syndrome (MAS).
