Fibrodysplasia ossificans progressiva, or FOP, is an extremely rare and debilitating disorder, in which bone tissue gradually replaces soft tissue throughout the body, extending the skeleton and “freezing” patients into position. FOP is an autosomal dominant disorder, and is believed to be caused by a mutation in the ACVR1 gene, which results in constitutively active BMP signaling. Clementia Pharmaceuticals is investigating Palovarotene as a RAR-gamma agonist capable of inhibiting BMP signaling, which may prevent heterotopic ossification and slow the progression of this devastating disease.