Generalized Epileptic Seizures in Fibrodysplasia Ossificans Progressiva Harboring a Recurrent Heterozygous Variant of the ACVR1 Gene (R206H).

Background: Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare disorder caused by heterozygous ACVR1 pathogenic variants and is characterized by both progressive heterotopic ossification of the soft tissues and congenital malformations of the great toe. In addition to pathological skeletal metamorphosis, patients with FOP experience diverse neurological symptoms such as chronic pain and involuntary movements; however, little is known about the association between FOP and epileptic seizures. Methods: We report the case of a young boy with FOP who sustained multiple major fractures due to epileptic loss of consciousness. Results: Based on generalized electroencephalographic abnormalities and the presence of myoclonic movements, the patient was diagnosed with juvenile myoclonic epilepsy. The absence of seizures was well-controlled with valproic acid, whereas occasional abrupt myoclonic movements of the hands and feet persisted. Conclusion: This case expands our understanding of the phenotypic diversity of FOP and the functional versatility of ACVR1-mediated bone morphogenetic protein (BMP) signaling.