Subsequently, on the basis of halluces malformation and flare-ups, a diagnosis of FOP was suspected, and sequencing of the ACVR1/ALK2 gene in DNA from a peripheral blood sample was performed, identifying a de novo recurrent c.617G>A (p.R206H) mutation, thus confirming the diagnosis of FOP. The gene discussed is ACVR1; the disease is fibrodysplasia ossificans progressiva.