Fibrodysplasia ossificans progressiva is a rare, progressive, disabling genetic disease presenting as ectopic ossification in soft tissues such as ligaments, muscles, and tendon aponeuroses. The pathogenesis involves a mutation in the ACVR1/ALK2 gene on chromosome 2, which is involved in the bone morphogenetic protein pathway. Affected individuals usually present with painful subcutaneous swellings that harden to form new bone within soft tissues. As the disease progresses, the ectopic bone fuses across joints, creating bony bridges that restrict and ultimately eliminate joint mobility. It often begins in the first decade of life and gradually worsens, rendering patients wheelchair-bound by the second decade of life. Common skeletal abnormalities include a shortened hallux, followed by malformed thumbs, fused cervical vertebrae, and clinodactyly. FOP is diagnosed based on the radiologic identification of heterotopic ossification in soft tissue. Genetic diagnosis is confirmatory. Symptomatic therapy provides relief in pain as there is currently no effective treatment available.
Sukriya et al. (Mon,) studied this question.