Fibrodysplasia ossificans progressiva (FOP, MIM 135100) is a rare autosomal 
dominant disorder characterized by postnatal progressive heterotopic 
ossification of the connective tissue and congenital malformation of the big 
toes. Recently, FOP has been associated with a specific mutation of ACVR1, the 
gene coding for a bone morphogenetic protein type I receptor. We report the case 
of a Moroccan patient with FOP carrying a rarely occurring mutation of ACVR1 
gene.