ACVR1 and fibrodysplasia ossificans progressiva: Kaplan Kaplan FS FS Classic and atypical fibrodysplasia ossificans progressiva (FOP) phenotypes are caused by mutations in the bone morphogenetic protein (BMP) type I receptor ACVR1 Classic and atypical fibrodysplasia ossificans progressiva (FOP) phenotypes are caused by mutations in the bone morphogenetic protein (BMP) type I receptor ACVR1 Hum Mutat Hum Mutat 2009 2009 30 30 3 3 379 379 390 390 10.1002/humu.20868 10.1002/humu.20868 supplied-pmid 19085907?