Fibrodysplasia Ossificans Progressiva
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What is fibrodysplasia ossificans progressiva?
Fibrodysplasia ossificans progressiva (FOP) is a disorder in which muscle tissue and connective tissue such as tendons and ligaments are gradually replaced by bone (ossify), forming bone outside the skeleton (extra-skeletal or heterotopic bone) that constrains movement. This process generally becomes noticeable in early childhood, starting with the neck and shoulders and proceeding down the body and into the limbs.
Extra-skeletal bone formation causes progressive loss of mobility as the joints become affected. Inability to fully open the mouth may cause difficulty in speaking and eating. Over time, people with this disorder may experience malnutrition due to their eating problems. They may also have breathing difficulties as a result of extra bone formation around the rib cage.
Any trauma to the muscles of an individual with fibrodysplasia ossificans progressiva, such as a fall or invasive medical procedures, may trigger episodes of muscle swelling and inflammation (myositis) followed by more rapid ossification in the injured area. Flare-ups may also be caused by viral illnesses such as influenza.
People with fibrodysplasia ossificans progressiva are generally born with malformed big toes. This abnormality of the big toes is a characteristic feature that helps to distinguish this disorder from other bone and muscle problems. Affected individuals may also have short thumbs and other skeletal abnormalities.
How common is fibrodysplasia ossificans progressiva?
Fibrodysplasia ossificans progressiva is a very rare disorder, believed to occur in approximately 1 in 2 million people worldwide. Several hundred cases have been reported.
What genes are related to fibrodysplasia ossificans progressiva?
Mutations in the ACVR1 gene cause fibrodysplasia ossificans progressiva.
The ACVR1 gene provides instructions for producing a member of a protein family called bone morphogenetic protein (BMP) type I receptors. The ACVR1 protein is found in many tissues of the body including skeletal muscle and cartilage. It helps to control the growth and development of the bones and muscles, including the process of cartilage being gradually replaced by bone (ossification) that occurs in normal skeletal maturation from birth to young adulthood.
Researchers believe that a mutation in the ACVR1 gene may change the shape of the receptor and disrupt its ability to attach (bind) to other molecules that control the receptor's activity. As a result, the receptor may be constantly turned on (constitutive activation). Constitutive activation of the receptor causes overgrowth of bone and cartilage and fusion of joints, resulting in the signs and symptoms of fibrodysplasia ossificans progressiva.
How do people inherit fibrodysplasia ossificans progressiva?
This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.
Most cases of fibrodysplasia ossificans progressiva result from new mutations in the gene. These cases occur in people with no history of the disorder in their family. In a few cases, an affected person has inherited the mutation from one affected parent.
Source: National Institutes of Health
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Studies from G. Lucotte and co-researchers yield new data on myositis ossificans
2009 JUN 2 - (NewsRx.com) -- According to a study from Paris, France, "Mutations of the noggin (NOG) and of the activin A type I receptor (ACVRI) genes in a series of twenty-seven French fibrodysplasia ossificans progressiva (FOP) patients: Fibrodisplasia ossificans progressiva (FOP) is a rare but very severe disease, characterised by congenital malformations of the toes and by progressive heterotopic ossification of muscles and joints. Two genes, the noggin (NOG) gene and the activin A type I receptor (ACVRI) gene, are involved in FOP." "In this study we have searched for the NOG and the 617G >A (ACVRI) imitations in a well characterized series of twenty-seven French FOP patients. Five NOG mutations (Delta 42, 274G >C, 275G >A, 276G >A, and 283G >A) have been found in seven (26%) of our FOP patients. The 617G >A mutation in the ACVRI gene is found in fourteen (52%) of the patients. With one exception (patient number 22), 617G >A and NOG mutations are mutually exclusive in patients," wrote G. Lucotte and colleagues. The researchers concluded: "Mutations 274G >C, 283G >A and 617G >A segregate with the trait in five different FOP families, some members of them being partially affected by the disease." Lucotte and colleagues published the results of their research in Genetic Counseling (MUTATIONS OF THE NOGGIN (NOG) AND OF THE ACTIVIN A TYPE I RECEPTOR (ACVR1) GENES IN A SERIES OF TWENTY-SEVEN FRENCH FIBRODYSPLASIA OSSIFICANS PROGRESSIVA (FOP) PATIENTS. Genetic Counseling, 2009;20(1):53-62). For additional information, contact G. Lucotte, Center Neurogenetics Molecular, 44 Rue Monge, F-75005 Paris, France. The publisher of the journal Genetic Counseling can be contacted at: Medecine Et Hygiene, CH de La Mousse 46, Case Postale 475, CH-1225 Chene-Bourg, Switzerland. Keywords: France, Paris, Genetic Counseling, Genetics, Heterotopic Ossification, Myositis Ossificans. This article was prepared by Life Science Weekly editors from staff and other reports. Copyright 2009, Life Science Weekly via NewsRx.com.
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