What are the symptoms? Most people with FOP have short big toes and some have additional abnormalities of the fingers or toes apparent at birth. The bone formation is usually first noticed in early childhood following isolated flare-ups of inflammatory swellings that resolve into hard lumps in the neck or along the spine. These lumps may be tender and gradually shrink as affected muscles are replaced by bone. The bony lumps in muscles appear usually spontaneously but can be provoked by injury to muscle by trauma or injection. The progressive physical disability is variable in the way it affects a person. There may be long periods of inactivity that can be several years in length. The bone formation eventually locks movement of the affected joints leading to profound immobility. What are the causes? FOP is caused by one of 14 different mutations in the activin A receptor, type I (ACVR1) gene on chromosome 2, with one genetic variant being predominant. How is it diagnosed? Definitive genetic testing early in life when malformed big toes or when unexplained swelling and hard lumps in muscles are observed can confirm a diagnosis of FOP. How is it treated? Currently there is no proven treatment for the condition. Anecdotal evidence suggests that a course of corticosteroids, begun within a short period of a flare-up, may help reduce the intense inflammation and tissue oedema seen in the early stages of the disease. Non-steroidal anti-inflammatory medications COX-2 Inhibitors and paracetamol may be useful in managing pain and chronic discomfort. Discovery of the causative gene has led to current clinical trials of possible treatments internationally. These agents act at different levels of the specific bone formation process seen in FOP. A retinoic acid receptor gamma agonist, palovarotene, is in a Phase 3 trial by Clementia Pharmaceuticals; a neutralising antibody to activin A, REGN2477, is in a phase 2 trial by Regeneron Pharmaceuticals and a kinase inhibitor, saracatinib, is in a Phase 2 trial under the Horizon 2020 programme of the European Commission. Details of these clinical trials may be found at clinicaltrials.gov or at cordis.europa.eu. Trauma and injury to the muscles often provokes bone formation at the injury site and speeds up progression of FOP. Intramuscular injections should be avoided if at all possible. Similarly, operations on the skeletal muscles to remove pieces of bone invariably result in increased bone formation, and should be avoided. Dental treatment may result in bone formation in the jaw muscles and individuals with FOP should inform their dentist. In medical emergencies general anaesthesia intubations should be avoided unless absolutely essential and even then only with expert anaesthesia assistance. Inheritance patterns and prenatal diagnosis Inheritance patternMost cases are sporadic and due to a new chromosome mutation in ACVR1. Children of affected individuals, however, have a 50% chance of inheriting FOP. Prenatal diagnosisFor pregnancy in someone affected by FOP prenatal diagnosis is now possible. Is there support? FOP Friends Email: email@example.comWebsite: fopfriends.com FOP Friends is a registered charity (no. 1147704) that provides information and support to those with FOP, their family and friends in the UK and those further afield. The Group actively raises awareness of the condition, and fundraises for research into treatments. Group details last updated October 2019. FOP UK Support Group Tel: 01772 339 296Email: MargaretParkes@btinternet.com This is a small network, established in 2000 offering informal support to affected individuals and their families. Group details last reviewed October 2019. International FOP Association (IFOPA) Tel: +001(407) 365-4194Email: firstname.lastname@example.orgWebsite: ifopa.org A non-profit organisation that provides hope to individuals with FOP and their families through education and support programs while funding research to find a cure. The IFOPA gives support to 1,000 individuals worldwide in over 50 countries. Group details added October 2019.