A second treatment modality, the retinoic acid receptor gamma (RARγ) agonist, palovarotene (Chakkalakal et al., 2016; Shimono et al., 2011; Sinha et al., 2016), has already shown some promise in clinical trials with adult FOP patients and enrollment is underway for safety and efficacy studies in children. This evidence concerns the gene RARG and fibrodysplasia ossificans progressiva.